TAB. XIII. 

 Chelone crassicostata. 



Fig. 



1 . Portion of the plastron seen from the under side. 



hs. The hyosternal ; ps, the hypostemal ; xs, the xiphisternal. 52 is the 

 coracoid, exposed by the removal of the right hyosternal. 



2. Cast in the matrix of a portion of the carapace of the same individual, showing 



the characteristic thickness of the ribs, pl,pL 



