THE OSTEOLOGY OF THE DIADECTIDAE AND THEIR 

 RELATIONS TO THE CHELYDOSAURIA 



E. C. CASE 

 State Normal School, Milwaukee, Wis. 



Our present knowledge of the family Diadectidae has been 

 obtained almost entirely from the writings of Cope. His work 

 was done upon fragmentary material from the Permian beds of 

 Texas — including, however, a few fine skulls — and was largely 

 of a systematic character. Scattered through his many papers 

 on this family are many brief notices and descriptions of anatomical 

 characters, but nowhere has he given even an approximately com- 

 plete description of the osteology. A summary of these brief 

 notices would have no value beyond the historical. Suffice it to 

 say that with his wonderful acumen he foresaw in his fragmentary 

 material much that the more perfect material here described has 

 made evident. For the bibliography and synonymy of the family 

 the reader is referred to Hay's Catalogue of the Fossil Vertebrata 

 of North America (Hay, 1902). 



The material upon which the following description is based 

 consists of several specimens collected by the author in the Permian 

 beds of Texas, and now in the collection of the University of Chicago. 

 The numbers given are the numbers of the University collection of 

 fossil vertebrates. 



The specimens consist of one nearly complete skeleton and 

 several less perfect, as follows: (1) a skeleton lacking only the 

 feet and free from distortion, No. 1075; ( 2 ) the anterior portion 

 of a skull with the complete right half of the lower jaw and a por- 

 tion of the left and a considerable portion of the vertebral column, 

 No. 1076; (3) the sacrum and seven presacral vertebrae of a much 

 larger specimen, No. 1077; (4) the major portion of a skull show- 

 ing the palatal region nearly perfectly, No. 1078; (5) an imperfect 

 skeleton showing the caudal region and some of the limb and foot 

 bones, No. 62. 



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