AVilliston.] Turtles. 367 



SYSTEMATIC POSITION. 



All things considered, I believe that the genus Desmatochelys 



must be located among the Cryptodira, in a distinct family of 



Baur's Chelonioidea. But this will necessitate revision of the 



characters hitherto attributed to both suborder and group. 



These may best be expressed by giving the characters in detail, 



as Baur 66 has expressed them, with the emendations shown in 



italics. 



CRYPTODIRA. 



Free nasals sometimes present ; a parieto-squamosal arch present 

 or absent ; descending process of prefrontals connected with 

 vomer ; stapes in an open groove of the quadrate or covered by 

 the quadrate behind ; pterygoids narrow in the middle, without 

 winglike lateral expansions, separating quadrate and basisphe- 

 noid ; epipterygoid free or not free ; dentary bones united. Cer- 

 vical vertebrse rarely icith stout transverse processes ; the posterior 

 cervicals with double or single articular faces ; sacral ribs well 

 developed and connected with centrum and neuroids ; pelvis 

 free from plastron and carapace. Epiplastra in contact with 

 hyoplastra ; entoplastron oval rhomboidal or T-shaped ; a more 

 or less complete series of peripheralia, more or less connected 



with the ribs. 



Chelonioidea. 



A parieto-squamosal arch ; articular faces between sixth and 

 seventh cervical vertebrae plane, nuchal with a distinct process 

 on the lower side for the articulation with the neuroid of the 

 eighth cervical ; no lateral processes of nuchal. One biconvex 

 cervical vertebra. 



1. — Desmatochelyidse. Palatine foramina present ; a descending 

 process of the parietals ; free nasals present ; limbs paddle- 

 shaped. Desmatochelys. 



2. — Cheloniidse. Palatine foramina not present ; a descending 

 process of the parietals ; no free nasals ; limbs paddle-shaped ; 

 claws one or two. Chelone, etc. 



3. — Dermochelyidse . No free nasals, no palatine foramina; 



66. Note on the Classification of the Cryptodira, Amer. Nat., July, 1893, p. 672. 



