38 



SCIENCE 



[N. S. Vol. LII. No. 1332 



Dr. Abel is professor of paleobiology at the 

 University of Vienna, a pupil of the great 

 Belgian scientist Louis Dollo, and a leading 

 authority in his profession. He is the author 

 of two earlier text-books, " Paleobiologie " and 

 "Die vorzeitlichen Saugethiere," the first of 

 which was reviewed in Science some years 

 ago. 



The present volume treats of the origin and 

 evolution of the various phyla (" Stamme ") 

 of vertebrates as shown in the paleontologic 

 record. It is concerned almost wholly with 

 extinct forms; and thanks to this limitation 

 the author has been able to give an unusually 

 full treatment and discussion, especially of 

 the reptiles and Amphibia. The illustrations, 

 while somewhat crude artistically, are ex- 

 cellent for teaching purposes, and its full dis- 

 cussion and fair treatment of recent foreign 

 discoveries are remarkable in a volume pre- 

 pared and published under war conditions. 

 From first to last Dr. Abel has endeavored to 

 discuss the evidence and give reasons for the 

 conclusions adopted, leaving the way open 

 for difference of opinion on many doubtful 

 problems. A certain imevenness of treatment 

 is manifest, both in the discussion and the 

 taxonomie arrangement, and many details of 

 presentation and classification are open to 

 criticism, as is inevitable in a volume of such 

 wide scope and fundamental treatment. From 

 errors of fact the book is singularly free. 



A classified list of the orders and families 

 accepted, with characteristic genera, serves as 

 a preliminary conspectus. To the fishes are 

 allotted 160 pages, partly introductory and 

 dealing chiefiy with the early and primitive 

 types. The vast variety of modern bony 

 fishes are treated in a very cursory manner. 

 The Amphibia cover 110 pages, devoted 

 mostly to the Paleozoic types and their rela- 

 tions to the higher vertebrates. The extinct 

 reptiles are quite fully treated, the discussion 

 covering some 355 pages. The most serious 

 criticisms to be made in this section are of 

 the splitting of the pterodactyls into two dis- 

 tinct orders, and the attempt to limit the 

 term dinosaurs to one of the two great orders 

 of gigantic land reptiles that are now under- 



stood to be included in the old usage of the 

 name. It would be better to retain it with 

 the old scope but in a general unsystematic 

 sense, like " pachyderms " among the mam- 

 mals. On the other hand, the discussion of 

 important researches and discoveries among 

 fossil reptiles and their bearing on the evolu- 

 tion of the vertebrates affords an excellent 

 synthesis of recent progress in the science. 

 Birds are a rather minor group among fossil 

 vertebrates, and 23 pages suffice to cover all 

 the important types in their evolution. 



The treatment of the Mammalia is rela- 

 tively brief, covering 16Y pages, passing very 

 briefly and uncritically over some of the 

 orders, and hardly touching upon the Pri- 

 mates, but more extended with other groups, 

 and especially authoritative in the Cetacea, 

 upon which the author has published several 

 very valuable researches. 



While by no means endorsing all of the 

 author's views upon problems of evolution 

 and classification, the present reviewer does 

 not hesitate to commend Dr. Abel's work as 

 highly authoritative and up to date, admirably 

 presented as to form and reliable as to fact. 

 The treatment of the subject differs widely 

 from that in the new edition of Zittel's 

 " Grundziige der Palaontologie," recently re- 

 vised by Schlosser and Broili, which affords 

 in many ways an excellent supplement for 

 Abel's volume, especially in its more compre- 

 hensive treatment of the Mammalia. 



W. D. Matthew 



American Museum op Natural History 



SPECIAL ARTICLES 



AN ULTRAMICROSCOPIC STUDY OF THE TWO 

 STAGES OF BLOOD COAGULATIONi 



Schmidt^ has described carefully the process 

 of coagulation as it may be followed with the 

 naked eye in the cell-free plasma of a slowly- 

 clotting mammalian blood (horse). He drew 

 attention to the fact that the process may be 



1 From the Physiological Laboratory of the Johns 

 Hopkins University. 



2 Schmidt, "Zur Blutlehre," Leipsig, 1893, p. 

 262. 



