No. 3.] PELVIS OF THE TESTUDINATA. 347 



In the two families mentioned we have about the same arrange- 

 ment as in the Chelydridae. In adult Cinosternidae we find the 

 three gastroids ossified, but very small ; the epigastroid never 



Fig. 3, — Dermatemys Mawii, Gray. 



Pelvis from below, from a sketch of Professor Riitimeyer. X, peculiar ossified pro- 

 cess, developed from the gastroid portion between the entoischia, also present in old 

 specimens of Chelydridce and Staurotypidoe. 



reaches the extension seen in the Chelydridae and Stauroty- 

 pidae ; entopubes and entoischia nearly touch each other, being 

 only separated by the small, diamond-shaped mesogastroid. It 

 may be that in very old specimens the mesogastroid becomes 

 absorbed by entopubes and entoischia. 



pleurale well developed; an entoplastron ; generally no rib on tenth dorsal; number 

 of peripherals, 1 1 . 



Dermatemydida. An anterior process on entoscapula near acetabulum; a pos- 

 terior process on coracoid near acetabulum; mesogastroid well developed, separating 

 completely entopubes and entoischia; no anterior process on ilium; rib-head of eighth 

 pleurale present; a rib on tenth dorsal which is free from the eighth pleurale; num- 

 ber of peripherals, 1 1 ; an entoplastron. 



Staurotypida (Claudius, Staurotypus). An anterior process on entoscapula near 

 acetabulum; a posterior process on coracoid near acetabulum; mesogastroid well de- 

 veloped, separating completely entopubes and entoischia; an anterior process on 

 ilium; rib-head on eighth pleurale absent; no rib on tenth dorsal; number of peri- 

 pherals, 10; an entoplastron. 



Cinosternida. Like .Staurotypidse, but mesogastroid reduced, not separating ento- 

 pubes and entoischia; no entoplastron. 



