1890.] Classification of the Testudinata. 535 
I. Amphichelydia. 
Nasals free ; a squamoso-parietal arch; descending processes of 
prefrontals joining vomer; stapes in an open groove of the quadrate ; 
pterygoids narrow in the middle, without wing-like lateral ex- 
pansions, separating quadrate and basisphenoid ; epipterygoid well 
developed and free ; dentary bones distinct. Cervical vertebrae with 
well-developed transverse processes, more in front of vertebra, with 
single articular faces, biconcave; dorsal vertebrz, sacral vertebrz, 
with well-developed ribs; ribs of sacral vertebrze connected with 
centrum and neuroid. Pelvis not anchylosed to the carapace 
and plastron. Epiplastra in contact with hyoplastra, entoplas- 
tron oval or rhomboidal; a complete series of peripheralia con- 
nected with the ribs. 
Il. Pleurodira. 
Nasals free, or united with prefrontals; a squamoso-parietal 
arch present or absent; descending processes of prefrontals 
absent; stapes in a groove of quadrate generally closed on the 
outside; pterygoids broad, forming wing-like lateral expansions, 
not separating quadrate and basisphenoid; epipterygoid not 
free; dentary bones distinct and united. Cervical vertebrz with 
well-developed transverse processes generally in middle of ver- 
tebra, with single articular faces; sacral ribs rudimentary; sacral 
ribs connected with neuroids. Pelvis anchylosed to carapace and 
plastron. Epiplastra in contact with hyoplastra, entoplastron 
oval or rhomboidal; a complete series of peripheralia connected 
with the ribs. 
Ill. Cryptodira. 
No free nasals; a parieto-squamosa] arch present or absent ; 
descending process of prefrontals connected with vomer ; stapes in 
an open grove, entirely covered by the quadrate behind; 
pterygoid narrow in the middle, without wing-like lateral expan- 
sions, separating quadrate and basisphenoid; epipterygoid free, 
or not free; dentary bones united. Cervical vertebrz with rudi- 
mentary transverse processes in front of vertebra; the posterior 


