TAB. XVIII^. 



Trionyx rivosus. 



Fig. 



1 . Outside view of hinder half of the carapace, nat. size. 

 ph — -pis. The fourth to the eighth costal plates inclusive. 



2. Inside view of the same specimen. 



ph — ph. The fourth to the eighth costal plates inclusive. 



5 — 9. The ribs (fifth to the ninth dorsal inclusive) connate with the above costal 



plates. 

 .96. The neural arch confluent with the sixth neural plate. 



