TAB. XIIL 



Chelone crassicostata. 



Fig. 



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



/is. The hyosternal ; ps, the hyposternal ; 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, pi, pi. 



