August 16, 1912] 



SCIENCE 



217 



eminent paleontologists is bound to attract 

 attention from the clear anatomical descrip- 

 tions of the forms under review and the con- 

 servative stand in the matter of conjectural 

 speculations. The book, as the author says, 

 " comprises a series of monographic studies, 

 together with briefer notes and descriptions, of 

 new or little-known amphibians and reptiles 

 from the Permian deposits of Texas and New 

 Mexico." 



The sources of material are mainly three: 

 the University of Chicago collection, made in 

 recent years by field parties under the charge 

 of Mr. Paul Miller or the author; earlier col- 

 lections of the University of Texas, made by 

 Professor E. C. Case; and finally the great 

 Marsh collection in the Peabody Museum at 

 Tale University, which proves an increasingly 

 fruitful field for research as its varied treas- 

 ures are brought to light. An interesting 

 comment upon our knowledge of reptilian 

 classification shows that the time is not yet 

 ripe to attempt phylogenies of the groups 

 other than the dinosaurs, crocodiles, phyto- 

 saurs, pterosaurs and rhynchosaurs, because 

 we are less sure of them than we were a dozen 

 years ago. " The more recent general classi- 

 fications of the reptiles by Cope, Osborn, 

 Boulenger, and others have offered suggestions 

 of value, but they are by no means the real 

 solutions of the reptilian and amphibian 

 phylogenies. The recent classifications of 

 Jaekel are not to be taken seriously," Cer- 

 tain morphological problems are discussed in 

 the following pages and the author has given 

 what seem to be the legitimate conclusions 

 regarding the immediate relationships of the 

 forms under discussion. The present work, 

 however, is offered more as a contribution to 

 our knowledge of ancient reptiles and am- 

 phibians, with such summaries and definitions, 

 based chiefly upon American forms, as our 

 knowledge at hand permits. The illustrations 

 of the work throughout were made by the 

 author. 



A summary of the genera from the Texas 

 Permian follows: Amphibia: Lysorophus, 

 Diplocaulus, T rimer orhachis (apparently ab- 

 sent from the upper part), Eryops, Oacops, 



Dissorophus, Aspidosaurus, Cardiacephalus. 

 Eeptilia: from the uppermost beds, Labido- 

 saurus, Naosaurus, Dimetrodon; from lower 

 horizons, Naosaurus, Dimetrodon, Clepsy- 

 drops, Varanosaurus, Trispondylus, Casea, 

 Armoscelis, Captorhinus, Diadectes, Sey- 

 mouria, etc., of which perhaps the most char- 

 acteristic are Labidosaurus of the upper and 

 Cricotus of the lower zones. Williston feels 

 confident, however,- that no definite line can be 

 made between the two divisions, and that at 

 present Clear Fork can be used in a general 

 way to designate the upper, and Wichita the, 

 lower part of the Texas deposits. 



Most of the important specimens come from 

 two isolated deposits known as the Cacops and 

 Craddock bone beds, the former of which is 

 among the most remarkable deposits of fossil 

 vertebrates known, especially when one con- 

 siders the almost universal rarity of Permian 

 remains. 



The Cacops deposit lies in the valley of the 

 Wichita in northern Texas about five miles 

 west of the Vernon road, not far from Indian 

 Creek, while the Craddock bone bed lies about 

 six miles northwest of Seymour, also in 

 northern Texas. The Tale material, on the 

 other hand, comes mainly from New Mexico, 

 all of the Marsh types coming from a deposit 

 which Williston has designated the Baldwin 

 bone bed. 



The research of Professors Williston and 

 Case is one of great promise, not only in the 

 ultimate clarifying of our vision with regard 

 to the anatomy and relationships of these 

 ancient forms, but in revealing to us the ac- 

 tual stages of transition between two great 

 vertebrate classes, the Amphibia and Eeptilia. 

 For his present book Professor Williston de- 

 serves our gratitude, and we look forward con- 

 fidently to still more notable results when his 

 researches shall have been completed. 



KicHARD SwANN Lull 



Tale Univeesitt 



Microhiology, for Agricultural and Domestic 

 Science Students. By Marshall and others. 

 Philadelphia, P. Blakiston's Son and Co. 

 In this work, of which Chas. E. Marshall 



