62 COPE 



present knowledge, as it includes but one family, the Oto- 

 coelidge, from the Permian formation of North America. 

 These reptiles possessed a carapace of transverse osseous 

 arches which extended across the back from side to side in 

 close contact. The anterior part of the scapular arch be- 

 low resembles the corresponding part of the plastron of a 

 tortoise. The temporal roof is excavated posteriorly for the 

 auricular meatus. The order is probably ancestral to the 

 Testudinata and the Pseudosuchia. 



The order Testudinata presents four subordinal modifi- 

 cations, as follows : 



I. No descending processes of the parietal bones. 

 Vertebrse and ribs free and separated from a 



bony exoskeleton ; no descending pro- 

 cesses of the parietals ; Athecse. 



II. A carapace and plastron, and descending process of 

 parietals. 



«, Sacral and caudal ribs articulating with neural 

 arches only. 



Neck bending in vertical plane, last cervical 

 articulating with first dorsal by zygapo- 

 physes only ; pelvis not anchylosed ; 

 marginal bones wanting or rudimental ; Trionychoidea. 



aa, Sacral and caudal ribs articulating with body 

 of vertebrse only. 



As the last ; but marginal bones present and 

 connected with ribs, and last cervical and 

 last dorsal vertebraj articulating by 

 bodies; pelvisnotanchylosed to plastron; Cryptodira. 



Neck bending in horizontal plane, the last 

 cervical and first dorsal vertebrse articu- 



