The genus Parasteiromys AMEGHINO, 1904 is revalidated, and P. friantae sp. nov. (Hystricognathi, Erethizontidae) from Colhuehuapian (early Miocene) sediments of the southern cliff of Colhue-Huapi Lake (Province of Chubut, Argentina), is described. The molar morphology of these taxa and of living porcupines adds new elements to understand the dental evolution of the Erethizontidae, and to propose the hypothetical ancestral molar pattern for this family. This pattern does not correspond to any of the morphologies traditionally proposed as ancestral for South American hystricognathous rodents. The proposed pattern is characterized by a metaloph disconnected from the posteroloph and oriented towards the hypocone, and the third loph incompletely developed with the lingual portion homologous to the mesolophule of Baluchimyinae (Chapattimyidae) from the Miocene of Pakistan. The inferred steps of the molar evolution of erethizontids towards the pentalophodont condition, considered derived for the family, are illustrated. This study strengthens the hypothesis placing erethizontids in a basal position among rodents of the suborder Hystricognathi.

  

 A new genus of hystricognath rodent with two new species, Soriamys gaimanensis and Soriamys ganganensis, from the Colhuehuapian Age (Early Miocene), Sarmiento Formation, of Patagonia is described. The first species comes from the south barranca of the valley of Rio Chubut, near Gaiman locality (Chubut Province). It is known through a great number of dental remains in different stages of wear. The teeth are protohypsodont, with cement in the principal valleys. P4 are simpler, more oval inoutline and without a differentiated hypocone-hypoflexus. Upper molars are pentalophodont in early stages of wear and become bilobated in middle and advanced stages; M3 have a temporary third posterior lobe due to the maintenance of the braquiflexus on the posterior wall of the tooth. Lower teeth have a completely asymrnetrical pattern in relation to the uppers. The molars are trilophodont, with only one complex crest in the trigonid composed of the fusion of the anterolophid and mesolophid. The dp4 have a derived pentalophodont pattern due to the loss or fusion of the mesolophid and the development of an accessory transverse crest between the anterolophid and metalophid. The second species is known through a complete skull and jaw and other skull fragments with the dentition, proceeding from Pampa de Gan Gan, Chubut province. Respect to the first species, the teeth are higher crowned, with an earlier occlusal simplification and a third posterior lobe of M3 more developed and persistent. The skull and jaws show many chinchilloid characters, such as jugal bone with an ascending process, concave palate, very prominent dorsal shelf of the masseteric fossa, nasolachrymal duct opened laterally on the maxillary and very developed lateral mandibular fossa. Moreover, Soriamys is closely related to Cephalomys by sharing a similar asymmetric dental pattern and other dental and mandibular characters. These two genera constitute a natural group, the Cephalomyidae, with peculiar dental characters, like the asymmetric pattem of the upper and lower teeth; Cephalomyopsis, and probably Litadontomys, can be considered part of this group. Scotamys and Perimys constitute a distinct lineage (the Neopiblemidae or Perimyidae), more closely related to the chinchillids. Many characters shared by cephalomyids, eocardiids and caviids suggest a closer affinity between the Chinchilloidea and the Cavioiidea as a whole. Abrocoma shows also an asymmetric dental pattern and other chinchilloid features that suggest some degree of relationship with the cephalomyids, still not well determined. 

Extensive collecting in previously known and new Middle Eocene rodent localities in the Subathu Group of the Rajauri and Reasi districts, Jammu and Kashmir (northwest Himalaya, India) has yielded over 500 isolated cheek teeth, numerous incisors and cheek tooth fragments, and two mandibular fragments with M/1-M/3. An analysis of this additional material and a restudy of that reported earlier from the Metka (Rajauri) area has revealed the presence of diverse Middle Eocene ctenodactyloid rodents in India. The assemblage comprises six genera and twelve species, viz.., Bírbalomys woodi, B. ibrahimshahi, B. sondaari, Basalomys vandermeuleni, B. ijlsti, B. lavocati, Chapattimys wilsoni, C. debruijni, Gumbatomys asifi, cf. Advenimus bohlini, cf. Petrokoslovia sp. indet. 1 and cf. Petrokoslovia sp. indet. 2. Most species of this assemblage are endemic to the Indian subcontinent and are referred to the Family Chapattimyidae. However, at least three taxa, viz.., cf. Advenimus bohlini, cf. Petrokoslovia sp.indet. 1 and cf. Pezrokoslovia sp. indet. 2 show close affinities with their Central and Eastern Asiatic contemporaries and are attributed to the Family Yuomyidae. The dentitions of most of the Middle Eocene rodents from India are described here in better detail thus providing more precise characterization than was available earlier. The taxonomie status of Basalomys, formerly a subgenus of Birbalomys has been raised to that of a genus. Basalomys vandermeuleni is here designated as the type species of Basalomys in place of B. ijlsti. The rodent assemblage from the Subathu Group is specifically similar to that from the coeval Kuldana Formation of Pakistan. The absence of Birbalomys ibrahimshahi and cf. Advenimus bohlini in Pakistan is related to sampling bias. The identifications of the Early Eocene rodents from Barbara Banda, Pakistan have been reexamined and the familial assignments of some of the Early and Middle Eocene rodents from Central and Eastern Asia have been discussed and reviewed in the light of recent discovery of early rodents in Mongolia.

  

Seventeen species of cricetid rodent are recognized and described from lower and middle Siwalik deposits in the Potwar Plateau of Pakistan. These species are grouped in three categories, characterized as subfamilies (e. g., Megacricetodontinae, Myocricetodontinae, and Dendromurinae); an additional and more abundant category of rodents from these deposits, the Democricetodontinae, is excluded from this study, and will be described in a later study. Fifteen of the species are new, and four new genera are described. The Siwalik cricetid taxa are : Megacricetodon aquilari, n. sp.; Megacricetodon sivalensis, n. sp.; Megacricetodon daamsi, n. sp.; Megacricetodon mythikos, n. sp.; Punjabemys downsi, n. gen. & n. sp.; Punjabemys leptos, n. gen. & n. sp.; Punjabemys mikros, n. gen. & n. sp.; Myocricetodon sivalensis, n. sp.;  Myocricetodon sp.; Dakkamyoides lavocati, n. gen. & n. sp.; Dakkamyoides perplexus, n. gen. & n. sp.; Dakkamys asiaticus, n. sp.; Dakkamys barryi, n. sp.; Dakkamys sp.; Paradakkamys chinjiensis, n. gen. & n. sp.; Potwarmus primitivus, n. gen.; and Potwarmus minimus, n. gen. & n. sp. This diverse record of middle Miocene small mammals illuminates a profound radiation of cricetid rodents in southem Asia, the effects of which were felt in Europe and Africa as well as the rest of Asia. 

The knowledge of the Anchilophini has been lately renewed by the discovery of a rather large amount of new material still largely unpublished. This new material offers the opportunity of a systematic revision of this tribe gathering those of European Eocene Equoidea which bear no mesostyle on upper check teeth and display a heavy trend to the molarization of premolars.

A cladistic analysis has made out two genera, Anchilophus (Paranchilophus included as a subgenus), characterized by a marked lophodonty and the transverse narrowness of the cheek teeth, a rather high hypsodonty, the frequent occurrence of "crochets" and "anticrochets" on the superior ones, and a rather weak molarization of the premolars, opposite to Metanchilophus n. gen. whose cheek teeth are more transversally elongated, less high, less lophodont, with cusps better distinct, enamel thicker and premolars more molarized on the whole.

Three species of Anchilophus are recognized, A. desmaresti, type species of the genus, A. (Paranchilophus) remyi and A. (Paranchilophus) jeanteli n. sp.

The genus Metanchilophus is more diversified with the species dumasi, radegondensis, gaudini (whose a new sub-species M. g. fontensis is defined), depereli, castrensis n. sp. and chaubeti n. sp.

The skull anatomy has been moreover described with several taxa; it brings to light (for all that one can generalize) that Anchilophini were light animals with a slender and elongated snout, a thin zygomatic arch, a rather developed encephalon with an advanced gyrencephaly.

The structure of the nasal opening together with the occurrence of epitympanic sinuses and the molarizing process of the premolars corroborate the attribution of this tribe to the family PalaeotheIiidae. 

The fauna from three new rodent localities (Castelmaurou, Grépiac-carrière et Grépiac-rive gauche) from Oligo-Miocene molasses of the Toulouse area is described. The one from Colomiers is completed. 11 species belonging to 4 families (Cricetidae, Eomyidae, Gliridae, Sciuridae) are present. The Miocene localities of Grépiac-carrière and Colomiers are correlated with Balizac, La Brète, Lambert and Lespignan. Grépiac-rive gauche is just a little older than these sites. Castelmaurou is somewhat younger than La Milloque and belongs to Oligocene. 

The fossil mammals collected from the Eocene of Hammada du Dra (northwest Sahara. Algeria) and two fragmentary teeth from the Lutetian of M'Bodione Dadere (Senegal) are described.
The fossils from the northwest Sahara come from a lacustrian deposit dated by charophytes (Raskyella aff. pecki, Raskyella n. sp.. Maedleriella lavocati, Maedleriella sp. et ? Peckichara sp.) as Middle Eocene or perhaps Lower Eocene (Gevin, Feist and Mongereau, 1974). Several hyracoids (3 or 4) identified from this formation extends the age of the family Pliohyracidae Osborn in Africa. Three forms appear to belong in the genera Megalohyrax, Titanohyrax and perhaps Bunohyrax which have been know until now only from the lower Oligocene of the Fayum (M. gevini n. sp. ; T. mongereaui n. sp.. ? Bunohyrax or Megalohyrax indet.). Another hyracoidof small size is referred to a new genus, Microhyrax (M. lavocati n. sp.).
Helioseus insolitus n. g. n. sp. is described without ordinal assignment. Azibius (Sudre, 1975) which has been the subject of questions and interpretations is reviewed.
Only one tooth from the Lutetian of M'Bodione Dadere is complete enough to interpret. lt probably belongs to a condylarth and demonstrates for the first time, the presence of the order in Africa. The second tooth is too fragmentary for comment.
In conclusion., the paleobiogeographic role of Africa at the end of the cretaceous and the beginning of the Cenozoic is discussed. 

Many types of insectivores have been described from specimens found in the Quercy phosphorites. These remains very often were not dated because they came from old collections. Recent excavations have permitted the situation of Amphidozotherium cayluxi FILHOL in the late Eocene. Two new genera are descrlbed based on material both from the old collections (Cryplotopos nov. g.) and from that recently recovered (Darbonetus nov. g., beginning of the middle Oligocene). Their systematic positions are revised and comparisons with American faunas are made. Amphidozotherium is not a talpid, but an erinaceoid belonging to an indeterminate family. Saturninia gracilis STHELIN is classified among the Nyctitheriinae, Myxomygale antiqua FILHOL among the Urotrichini Talpinae, and the genus Geotypus POMEL among the Scaptonichini Talpinae. A new study of the talpids from Auvergne has been rendered necessary. During the late Eocene and Oligocene precise morphology relationships existed between certain insectivores of Europe and North America. 

The dentitions as well as one complete and several partial skeletons of Equoids from the Eocene lignite beds of the Geiseltal locality are revised. Instead of 13 species distinguished up to now 3 chronoclines with 5 species and 3 separate species are recognized (text. fig. 1). Propalaeotherium hassiacum HAUPT, 1925 is evolving into Propalaeotherium isselanum (CUVIER, 1824) between the levels of the « obere Unterkohle ›› and the « untere Mittelkohle ›› of the Geiseltal section. Propalaeotherium argentonicum GERVAIS, 1849 is shown to be present in the « untere Unterkohle ››, whereas Lophiotherium pygmaeum (DEPERET,1901) occurs in the « obere Mittelkohle ›› and in the « oberes Hauptmittel ››. Plagiolophus cartieri STEHLIN, 1904 appears during the transition from the « Mittelkohle ›› into the « Oberkohle ›› as the earliest true Palaeothere. Therefore the « Oberkohle ›› is already regarded as Upper Eocene. This is corroborated by the occurrence of a phyletic descendant of Propalaeatherium parvulum (Propalaeotherium n.sp.) in the middle and upper "Oberkohle " because this species appears otherwise for the first time at the mammal level of Lissieu. On the other hand Propachynolophus gaudryz (LEMOINE, 1878) described by Matthes (1977) from the « untere Unterkohle ›› turns out te be in fact a Phenacodont. Thus the decisive argument for classifying the « untere Unterkohle ›› as Lower Eocene has to be dropped. Biostratigraphically the « Unterkohle ›› and the «Basishauptrnittel ›› correspond with the lower Middle Eocene (mammal level of Messel), whereas the «unteres Hauptmittel ›› and the « untere Mittelkohle ›› are equivalent to the middle part of the middle Eocene (mammal level of lssel), and the « obere Mittelkohle ›› together with the « oberes Hauptmittel ›› coincide with the upper Middle Eocene (mammal level of Bouxwiller). 

Herein we describe a small but relatively diverse assemblage of fossil fishes derived from the lower Oligocene (Rupelian) Red Bluff Clay at site AMo-9 in Monroe County, Alabama, USA. Identified amongst the remains are 15 unequivocal taxa representing 11 families within five orders, and one additional taxon represents an unknown order and family. Taxa identified include Eostegostoma sp., Otodus (Carcharocles) sp., Mitsukurinidae/Carchariidae indet., Macrorhizodus praecursor, Galeorhinus sp., Negaprion gilmorei, Physogaleus sp., “Sphyrna” sp., Galeocerdo sp., cf. “Aetobatus” sp., Sphyraena sp., Xiphiorhynchus kimblalocki, Xiphiorhynchus sp., Cylindracanthus ornatus, and C. rectus. Several additional fossils could not be identified beyond Lamniformes, Carcharhiniformes, and Teleostei, but they likely belong to one of the identified taxa within this paleofauna. All of the fishes previously reported from the Red Bluff Clay within the entirety of the Gulf Coastal Plain of the USA are otolith-based, and each of the 15 unequivocal taxa reported herein are important new records for this lithostratigraphic unit. In particular, the Eostegostoma sp. and Xiphiorhynchus spp. specimens represent the first occurrences of these taxa in Alabama. The specimens of C. ornatus, Eostegostoma sp., and X. kimblalocki are stratigraphic and temporal range extensions from the middle and late Eocene into the Rupelian Stage of the Oligocene. Other described taxa may represent transitional forms between those described from the late Eocene and late Oligocene within the region. This study provides a tantalizing preliminary view into faunal transitions that occurred amongst marine fishes across the Eocene/Oligocene boundary within the Gulf Coastal Plain of the USA. 

The late Pliocene site (MN 16) of Balaruc II (Hérault, France) has provided remains of the following amphibians and reptiles: Chelotriton pliocenicus nov. sp. and Triturus marmoratus (Salamandridae), cf. Rana (Ranidae), cf. Blanus (Amphisbaenidae), cf. Agama (Agamidae),  Gekkonidae indet., Lacerta s.l. (Lacertidae), "Ophisaurus" sp. (Anguidae), Michauxophis occitanus (Aniliidae), Erycinae indet. (Boidae), Elaphe cf. E. longissima and Malpolon sp. (Colubridae), cf. Naja (Elapidae) and Vipera sp. (Viperidae). The salamandrid Chelotriton pliocenicus and the aniliid Michauxophis occitanus constitute, up to now, the only records of these groups in the European Pliocene. The fauna is indicative of a warm, dry
subtropical climate. 

A critical review on the literature about the parataxonomy of amniote eggshells reasserts the great interest of this systematics tool for the progress of dinosaur eggshell paleontology. However, shedding light on its limits, we propose to give up the use of the basic types - morphotypes key system. 

Tarsals that can be confidently attributed to Paschatheríum dolloi from Dormaal (Belgium) are described. The astragalus is short; its broad neck is set at an angle of 30 degrees to the trochlea. The trochlea is pulley-shaped and proximally extended. There is no astragalar foramen. The medial tibial facet extends distally in a cup deeply excavated in the neck and buttressed. The sustentacular facet extends toward the navicular facet but is not fully confluent with it. The calcaneum bears a proximo-distally extended proximal facet for the astragalus. A relatively large peroneal tubercle projects from the body, and is situated distally. Functionally, the trochlea indicates extensive flexion-extension movements of the foot. Calcaneo-astragalar facets indicate sliding and rotation between the two tarsals. The inclination of the navicular facet suggests frequent foot inversion. The peroneal tubercle reflects good muscular capacities for foot rotation. Overall morphology is interpreted as a scansorial adaptation similar to that of sciurids.Comparisons are made with the tarsals of Macrocranion vandebroeki from Dormaal and Hyopsodus paulus from the Bridgerian of Wyoming. Some similarities between the astragali of Paschatherium and Macrocraníon (trochlea) are interpreted as convergences for rapid locomotion. However absence of mobility at the lower ankle and midtarsal joints in M. vandebroekzi suggests that this species was cursorial, as is known for M. tenerum from Messel. Similarities in the calcanea of Paschatherium and Hyopsodus are probably the result of close phylogenetic relations, and confirm the placement of Paschatherium in the hyopsodontids. The differences in the calcanea of Paschatherium and Macrocranion underline that Paschatherium is distinct from erinaceomorph insectivores. The differences in astragalar morphology between Paschatherium and Hyopsodus show that a marked adaptive divergence separates the two genera. We speculate about the common occurrence of a deep tibial cup (“cotylar fossa”) and a pulley-shaped trochlea in Paschatherium and hyracoids, suggesting that an adaptive scenario similar to that having led to Paschatherium (scansoriality) might explain the acquisition of the peculiar hyracoid tarsal characters; such a scenario contradicts the concept of Pantomesaxonia. Other peculiar characters of Hyopsodus suggest that hyopsodontids might be given more consideration in the search for hyracoid (and tethythere) origins. 

More than 400 paleontological type-specimens housed in the Montpellier University collections have been inventoried in this catalogue which includes charophytes, Paleozoic plants, brachiopodes, molluscs, arthropodes and vertebrates (selachians, amphibians, reptiles, birds and mammals). The vertebrates have been treated exhaustively in the catalogue and one can consider that it includes most of the type specimens deposited in the Montpelier II collections. 

The present study of Artiodactyla from the Middle Eocene of the Geiseltal lignite beds concems systematics, biostratigraphy, and palaeoecology on the basis of 174 specimens: isolated remains to more complete skeletons. Instead of the formerly known five species of two families are now recognized 14 species of the Diacodexeidae, Dichobunidae, Cebochoeridae, and Haplobunodontidae. New species are Aumelasia maniai, Anthracobunodon neumarkensis, Masillabune franzeni. Four species of the Geiseltalfauna are definitely known from elswere, and five species are closely related to those from other European localities. Evidently the faunal situation of artiodactyls during the Middle Eocene of Europe was largely uniform. The distribution of artiodactyls within the sequence of the Geiseltal strata corroborates the biostratigraphical concept of the land mammal age Geiseltalian (Franzen & Haubold l986b) as well as the mammalian reference levels MP 11-13 (Franzen 1987). Reconstructions of the skulls and skeletons allow conclusions on the functional morphology and palaeoecology of the artiodactyls of the European Middle Eocene 

Record of life and works of Henri Menu, French zoologist, contributor to the knowledge of living and fossil bats. 

The first lists of Insectivores (Erinaceidae, Talpidae and Soricidae) from the Pliocene beds of Southern France and North-East Spain are given in this paper. The material from twelve localities is studied. These localities are geographically situated in Languedoc (Celleneuve, Vendargues, Nîmes, Sète, Balaruc 2 and Seynes), in Roussillon (Terrats, Serrats-d'en-Vacquer, Château d'eau and Mont-Hélène) and in North-East Spain (Layna, Medas Islands and Puebla de Valverde). These faunas correspond to the Early, Middle and Late Pliocene. 1 to 8 taxa are identified in these localities and 14 specific taxa are presently listed for this period in this area. Two new specific taxa are described as Galerix depereti nov. sp. from all the Early Pliocene localities in the North-Pyrenean area and as Desmanella gardiolensis nov. sp. from Balaruc 2. For this small mammals, two faunal assemblages are recognized. The first one is dated from the Early Pliocene (F 1, 2 and 3 zones in Aguilar et Michaux) and is characterized by Galerix depereti and rare and little diversified Soricids. The second one is Late Pliocene in age (zones G 2 and G 3). The fossils of the genus Talpa are relatively abundant and the Soricids are diversified and very abundant. The Middle Pliocene (zone G 1) is a transitional period. ln these faunas, most of the insectivore genera are known from the European Late Miocene beds (8 on 10). This fact demonstrates a relative continuity between the invectivore faunas from the Late Miocene to the Early Pliocene. In conclusion, somme paleoecological considerations are suggested.
  

The investigations undertaken at Crivadia (Hateg Depression, Hunedoara District, Romania), the type locality of Crivadiatherium mackennai RADULESCO el al. (Radulesco, Iliesco et lliesco, 1976), led to the discovery of remains of a new Embrithopod. Close to the above mentioned species, but larger in size, this animal is here described as a new species of Crivadiatherium, C. iliescui. ln addition, the comparison made between the forms indicated above and Palaeaamasía kansui OZANSOY from the Eocene deposits of Anatolia (Ozansoy, 1966; Sen et Heintz, 1979) showed that the latter species included a heterogeneous material; this permitted us to distinguish the form in the Anatolian locality Ciçekdag-Arabin Kôyü under the name Palaeoamasia sp. The geographical distribution and diversity of the Embrithopod species under discussion (Balkan, Anatolia) support the idea of an eurasiatic origin of this group and seem to suggest the existence during the Eocene of a particular faunal province in south-eastern Europe. 

Paleosols and the taphonomy of vertebrate fossils in the Eocene Kuldana Formation of northern Pakistan provide important information on the preservation and time-averaging of fossil assemblages. Morphologic, mineralogic, and chemical data as well as comparisons with Quaternary soils suggest that Kuldana paleosols formed under generally dry and oxidizing conditions over time intervals of less than 100 000 years and perhaps as short as 1000 years. The distribution of carbonate in Kuldana paleosols further indicates that the upper half of the profiles were acidic whereas the lower halves were alkaline. Vertebrate fossils are rare in Kuldana paleosols and occur primarily in well-cemented sandstones and conglomerates with abundant micritic and iron-stained nodules that were reworked from floodplain soils. The scarcity of vertebrate remains in Kuldana paleosols probably reflects a combination of acidic, dry, and oxidizing conditions in the upper half of the profiles and rapid floodplain sedimentation. Comparisons between the taphonomic characteristics of Kuldana channel fossil assemblages and bone accumulations in modem rivers provide a basis for estimating the length of time represented by Kuldana fossils from several important localities. Vertebrate fossil assemblages from Barbora Banda are characterized by a low-diversity paleofauna, partially articulated skeletons, and bones that are sorted by size and shape. Comparison with bone accumulations in modern rivers suggests that the fossils from Barbora Banda accumulated in 1 to 10 years. Vertebrate fossils from the Lower Kuldana in the Kala Chitta Hills region, typified by locality H-GSP 62, are characterized by a high-diversity paleofauna and generally random and unsorted fossil bone distributions, which suggest that the fossils from these localities represent longer time intervals than the Barbora Banda fossils. Based on the time estimates for Kuldana paleosol development, fossil assemblages in Kuldana channel deposits in the Kala Chitta Hills region probably represent time intervals of about 1000 years. 

The first part of this study was devoted to a descriptive analysis of teeth morphologies among the vespertilionine bats. This leads now to a tentative synthesis, providing views on the systematics of the group. The results could be seen according to three distinct but closely related purposes : 1 - the sorting of the genera contents in order to conform the genera units to homogeneous taxa that could represent natural issues of evolutionary lineages ; 2 - the investigation of relationships between extant genera in order to infer the possibilities of common origin ; 3 - according to the preceeding items and to the observed evolutionary trends, a tentative phylogeny, modest and cautious. The contents of many genera are sorted : Leuconoe is removed from subgeneric to generic position, whereas Myotis becomes a subgenus of it ; the myotodont species are cleared away from the Pipistrellus genus ; Glischropus and Scotozous are synonymized within Pipistrellus ; Hypsugo is raised to the generic level ; some species previously ranged within Pipistrellus will form provisionally a collective group, Attalepharca nov. ; the Eptesicus genus is broken up, the excluded species being grouped within Nycterikaupius gen. nov. ; the Nycticeini tribe is defined again after exclusion of Otonycteris , Scotoecus, Scotophilus , and addition of Hesperoptenus ; the species la io and Pipistrellus tasmaniensis are removed to Eptesicus (n.s.) and Pipistrellus dormeri to Scotoecus. Groupings of genera are stated according to the main evolutionary trends of I1/. The relevance of these is often warranted by close morphologic similarities of other teeth. This leads to a recognition of the major evolutionary radiations which occurred in the group. The filiations schematized at the end of the work show the dental relationships observed between the extant genera, and could represent a phylogenic framework. Two major facts are to be underlined : 1- the early divergence of leuconoids ; 2 - the successives crossings to myotodonty from the nyctaloid flow. Fossil data from the literature are punctually and tentatively incorporated within phylogenic sketches.