NOVEMBEK 1, 1901.] 



SCIENCE. 



699 



graphic evidence leads to the conclusion that 

 these regions have repeatedly been land areas, 

 and that the successive invasions of the sea 

 found the lands so low and flat as to offer no 

 scarps for the sea to work upon. Regarding 

 Brittany, it is remarked that littoral deposits 

 somewhat to the north (bordering the Cotentin) 

 have been produced in the same neighborhood 

 and at altitudes difl^ering only by a few meters 

 during eleven different periods beginning 

 with the Trias, thus indicating an astonishing 

 stability of this region during the time of its 

 denudation to the peneplain form. Marine 

 erosion is therefore excluded, and the pene- 

 plains are ascribed to subaerial denudation. 



W. M. Davis. 



RECENT ZOO-PALEONTOLOGY. 

 FOSSIL REPTILES OF EUROPE. 



The latest paper upon the Pterosaurs is by Dr. 

 Felix Plieninger.* Dr. Eberhard Fraasf pro- 

 poses the name Thalattosuchia as a new group 

 of marine crocodiles of the Jurassic formation, 

 differing widely from all others in the extreme 

 adaptation for aquatic life, especially in the total 

 disappearance of the dermal armature and in 

 the complete conversion of the limbs into pad- 

 dles. The three chief genera Metriorhynchus, 

 Geosaurus and Dacosaurus were placed by von 

 Zittel in the family Metriorhynchidse, of the sub- 

 order Eusuchia. But according to Fraas they 

 deserve a wider separation, since while most 

 nearly related to the long-snouted crocodiles 

 (Longirostres), they by no means present a tran- 

 sition to the short-snouted (Brevirostres), but 

 represent an entirely independent group, exclu- 

 sively adapted to marine life. The superficial 

 resemblance of the skull to that of Ichthyosaurs 

 is intensified by the reduction of the character- 

 istic crocodilian sculpture and by the ossifica- 

 tion of the sclerotic coat of the eye. The details, 

 however, are quite distinctive. This constitutes 

 the fifth independent group of marine rep- 

 tiles, the others being the Plesiosaurs, Ichthyo- 

 saurs, Mosasaurs and Chelonians. 



*'Pal^ontographica,' Vol. XLVIII., 1901. 

 t'Jahresb. d. Ver. f. vaterl. Naturk. in Wartt,' 

 1901, p. 408. 



marsh's COLLECTION OF BRIDGER MAMMALIA. 



This unique collection of Eocene mammalia 

 has been placed by Professors Beecher and 

 Dana, of the Peabody Museum, in the hands of 

 Dr. J. L. Wortman for systematic description.* 

 As Dr.- Wortman remarks, " The importance of 

 the subject to the student of mammalogy 

 can scarcely be overestimated, since these 

 epochs witnessed the beginnings and branching 

 off of many groups destined to play such a 

 prominent part in succeeding mammalian de- 

 velopment. This fact was fully appreciated by 

 Professor Marsh, and he spared neither pains 

 nor expense in making the collections as com- 

 plete as possible." In the first part, on the 

 Carnivora, Dr. Wortman proposes an important 

 and what may prove permanent change, in 

 grouping with the modern Carnivores all the 

 Creodonta that are closely related to them under 

 the new suborder Carnassidentia, and retaining 

 the suborder Creodonta (Cope) only for the an- 

 cient types that are entirely aberrant. Valu- 

 able notes are given upon the ancestral foxes 

 of Wyoming, and the evolution is traced as far 

 as the Uinta. The author believes that all the 

 placentals had a direct marsupial ancestry, not 

 far removed from the mesozoic carnivorous 

 marsupials. Attention may be called to the 

 fact, opposed to this view, that all the mesozoic 

 marsupials known have a highly specialized 

 character, with inflected jaw and aborted milk- 

 dentition, so that they cannot be considered an- 

 cestral to the placentals. The value of these 

 papers for future reference would be increased 

 by the insertion of the museum numbers in 

 connection with all descriptions and figures. 



pleistocene horses of north AMERICA. f 



In the preglacial sands of the west and the 

 cave and gravel deposits of the east, remains of 

 horses are extremely numerous ; no less than 

 twenty-five species have been proposed and the 

 nomenclature has been in a state of dire con- 



* ' Studies on Eocene Mammalia in the Marsh Col- 

 lection, Peabody Museum,' Part I. Carnivora, Amer. 

 Jour. Sei., May aud June, 1901. 



f Tooth Characters and Revision of the North 

 American Species of the Genus Eqiius. By J. W. 

 Gidley. Bull. Amer. Mas. Natural History, Vol. XIV., 

 Art. IX., pp. 91-141, May, 1901. 



