Febbuaey 17, 1911] 



SCIENCE 



251 



any one to be expert in more than one of its 

 half dozen branches. But the writer does ap- 

 preciate the merits of the work, since it will 

 relieve him, in large part, as also many others, 

 of the almost insurmountable difficulties he 

 has encountered in attempting to keep abreast 

 of the discoveries in mammalian paleontology. 



In brief, the work deals with extinct faunas, 

 rather than with the evolution of mammals, 

 with " time and place " rather than with " de- 

 scent " ; as the author says, it is " a study of 

 the sources or birthplaces of the several kinds 

 of mammals, of their competitions, migra- 

 tions, and extinctions, and of the time and 

 places of the occurrence of these great events 

 in the world's history." As such, after the 

 introduction, of which more later, it deals 

 with the faunas of each great division, And its 

 minor subdivisions, so far as possible, of the 

 Cenozoic, geologically, geographically, envi- 

 ronmentally and faunistically. The author 

 makes use of whatever available assistance is 

 ailorded by other branches of paleontology in 

 his paleogeographic and climatic discussions, 

 though not always with the same expertness 

 that he shows in his more special field of 

 research, the mammals, as for instance, the 

 statement on page 106 that Helagris is the 

 oldest known American serpent. Marsh years 

 ago described the serpent Coniophis from the 

 Lance beds, and the present writer can con- 

 firm his determination; and he also objects to 

 calling Champsosaurus either aquatic or a 

 lizard. But the few such errors that the 

 writer has observed are trivial, and it would 

 be supererogatory to search for others. 



To give even a resume of the work would 

 be beyond the limits of this article. Perhaps 

 no part, other than the introductory chapter, 

 will be of more general interest than that 

 dealing with the Pleistocene, and especially 

 that with man in his faunal and time rela- 

 tions. The writer is one who still believes, 

 notwithstanding the objections raised by geol- 

 ogists and anthropologists, that there is pale- 

 ontological evidence of man's contemporaneity 

 in North America with some, at least, of the 

 extinct mammals, and he finds of interest the 

 summary of such evidence. 



By the aid of sections, maps and photographs 

 every known horizon of the North American 

 Cenozoic yielding vertebrate fossils is located 

 and defined, and correlated, so far as possible, 

 with the horizons of other lands. For the 

 American deposits and faunas, and to a very 

 large extent for those of other lands, the data 

 of this work have been brought together from 

 original sources, and the writer has sufiicient 

 acquaintance with the literature to perceive 

 that very few indeed have been omitted or 

 overlooked. The numerous figures of skele- 

 tons, and photographs of restorations chiefly 

 from the able brush of C. R. Knight, will espe- 

 cially commend the work to the general reader. 

 Many of these figures have become familiar 

 to students within recent years in special 

 works and in texts. They are here brought 

 together and numerous others added. 



Not the least useful part of the work to the 

 zoologist is the summary of the classification 

 of the Mammalia in the appendix, with a list 

 of the known genera, their range and dis- 

 tribution. That it will be accepted imme- 

 diately by zoologists in its entirety is hardly 

 probable. The writer for one, as a student of 

 the extinct reptiles, demurs at the unreserved 

 location of the Multituberculata among the 

 Marsupialia, notwithstanding the apparently 

 convincing discoveries of Gidley. Tritylodon 

 stands, confessedly, somewhere near the di- 

 viding line between the Reptllia and Mam- 

 malia, and the relationships between Tritylo- 

 don and the Multituberculata seem so clear 

 that one can not accept the necessary conclu- 

 sion that the reptiles evolved directly into 

 marsupials. That some or all of the Multi- 

 tuberculata will some time be proved to be 

 oviparous the writer firmly believes, and there 

 are others who believe so with him. The 

 author accepts not less than thirty-four orders 

 of Placentals, arranged under four chief 

 groups, the Fnguiculata, Ungulata, Primates 

 and Cetacea. "We need to add but three or 

 four more " cohorts " of equivalent rank — and 

 the author may rest assured that some of his 

 zealous colleagues will promptly do so — and 

 we again have essentially the older classifica- 

 tion under new names. There is a similar 



