This paper is mainly devoted to the systematics of rodents from two middle Eocene (Bartonian) localities: Chéry-Chartreuve and Rocourt-Saint-Martin (Aisne, Eastern Paris Basin). These two localities are stratigraphically located slightly above the Auversian sands. The two faunas, which comprise 11 and 8 taxa, respectively, are very different in their composition. That of Rocourt-Saint-Martin shows strong similarities with that of the geographically very close locality of Grisolles, referred to the MP16 mammalian Reference level. The very distinct fauna of Chéry-Chartreuve includes a new species of Ailuravinae, Ailuravus nov.sp, and some teeth of the theridomyid Protadelomys, which represent archaic elements in the fauna. The most abundant species of the locality represents a new genus of primitive Theridomyidae. The presence of some teeth belonging to a new species of large Remyinae, Remys nov. sp., of Elfomys engesseri HOOKER & WEIDMANN, and a population of small dimensions referred to the genus Estellomys allow a correlation with Les Alleveys (Switzerland), with however some differences that would indicate an older age for Chéry-Chartreuve. Situated at the base of the "Marinesian" from the Bassin de Paris, this fauna is unquestionably different from those referred to the MP16 reference level and could represent an older level for which the macrofauna remains very poorly known. Conversely, the comparison of rodents from La Livinière II with those present in MP16 faunas, especially those of Robiac (Gard), shows a great similarity between both localities. This casts doubts on whether to keep this La Livinière II faunule to define the current MP15 reference level, while the biostratigraphical position of Pontils 26 (Spain), previously referred to this level, is reconsidered. Chery Chartreuse could be a good candidate for a new definition of the MP15 reference level. 

The Paleogene faunal assemblage from Antofagasta de la Sierra (Catamarca, Argentina), is here presented, both in its geological and systematic aspects. The fossil bearing levels are referred to the Geste Formation (Pastos Grandes "Group"). The described specimens belong to the Classes Reptilia (Orders Crocodylia, Serpentes and Chelonii) and Mammalia (three taxa from the Superorder Marsupialia, representatives of the Orders Edentata, Condylarthra, Pyrotheria and Astrapotheria, and six families of the Order Notoungulata). This fauna is referred to the Mustersan Age, which in Patagonia represents the Middle Eocene. Such chronologic assignment is based on the presence of characteristic taxa, their evolutionary stage and on stratigraphic evidence. Finally, a brief comparison with other faunal assemblages from the Early Tertiary of Argentina and Chile, is presented. 

Three erinaceomorph species are known from the early Middle Eocene of Grube Messel near Darmstadt, Germany, which are referred to the family Amphilemuridae. Pholidocercus hassiacus, Macrocranion tupaiodon, and Macrocranion tenerum showed extraordinary adaptations to their different life strategies, and several of their specializations are unknown among living insectivores. Pholídocercus was a well-defended robust animal with an opportunistic feeding strategy. Macrocraníon zupaiodon was a slender forest floor-dweller with saltatorial specializations to escape from predators; fishes were the preferred component of its omnivorous diet. Macrocranion tenerum exhibited a combination of both survival strategies, extremely elongated hind limbs for rapid and even ricochetal flight and a spiny exterior as an effective protective device; it was probably specialized for feeding on ants. Thus, closely related, omnivorous-insectivorous forest floor-dwellers could exploit the Messel ecosystem. 

A new genus and species of haplobunodontid artiodactyl, Hallebune krumbiegeli nov. gen. nov. sp., is described from the middle Eocene Geiseltal Fauna (Saxon-Anhalt, Germany). Its stratigraphic range is restricted to the MP 13 ("obere Mittelkohle") of the Geiseltalian. The material consists of seven fragments, representing both upper and lower jaws. It is indicated, that H. krumbiegeli was a small bunodont herbivore. The size and primitive character of the teeth suggest that the genus possibly is directly derived from Diacodexeidae.The new material forms the basis for reinterpreting the haplobunodontid phylogeny. 

Palaeotis weigelti, from the Middle Eocene of central Europe, is a flightless, paleognathous bird. It appears to be a member of the ostrich lineage on the basis of trivial derived characters. It is a very primitive ratite, however, and does not possess any of the highly specialized cursorial adaptations that characterize the modern steppe -and savanna- dwelling ostriches. 

New dental and skeletal material referable to Palaeochiropteryx tupaiodon from the Middle Eocene locality of
Messel (G.F.R.) is studied, which provides additions to the previously gained knowledge of this european genus. Dental specimens from Geiseltal (G.D.R.), also of Middle Eocene age, allow us to analyze Cecilionycteria prisca. Some of these are separated to establish a new genus, Matthesia, and two new species, M. germanica and M. ? insolita. 

The faunal list of the mammals collected at the locality of Aumelas (Hérault, France) is revised. For the first
time this Middle Eocene locality is precisely settled in the european chronological scale of "niveaux repères", between the levels of Bouxwiller and Egerkingen, in Uppermost Lutetian.
A new Dichobunid from the site is described : Aumelasia gabineaudi n. g., n. sp. This new genus has primitive characters. and it may be in the descent of the Lower Eocene Protodichobune. 

The Pantolestidae from the middle eocene of Bouxwiller are the subject of a detailed study. Buxolestes hammeli (n. g., n. sp.) is not closely related to any other European or North American form described until now; it presents, however, some characters in common with Pantolestes, a form of the same age from North America. A parallel evolution from a common ancestral form could explain this ressemblance.
Another form (gen. and sp. indet.) accompanies Buxolertes hammeli in the Bouxwiller fauna.
  

The description of new material from three classic middle Eocene localities of western Europe permits the addition of details to the systematics of primitive Pseudosciurids. The cranial anatomy of Protadelomys cartieri (STEHLIN and SCHAUB) from Egerkingen is described here and compared to that of the Adelomyines from the late Eocene, until now the only ones known. The morphologic and biometric study of the dentition of P. cartieri compared to that of P. alsaticus n. sp. from Bouxwiller and P. Iugdunensis n. sp. from Lissieu, forms respectively older and younger than P. cartieri, permits the evolutionary tendencies of the group to be demonstrated and shows that notable differences in age exist between these localities. This ensemble of forms can constitute a valuable guide lineage in the establishment of a fine stratigraphy of the period. Other less well known lineages are present at Egerkingen along with P. cartieri. They can be related to genera that have been noted int he late Eocene. In conclusion, a criticism of recent zonation proposals, made by divers authors, completes this article.