EXPLANATION OF PLATE XXXVIII. 



Restorations of crania of three species of Pi/lhonomorjilui, viewed from above, oue-tbinl nalural size: 

 rmj-., premaxillary bone; i/x., maxillary; Prf., prefrontal; Fi:, frontal; Pof., postfrontal; Fa., 

 parietal; Pro., prootio ; £xo., exoccipital ; Opo., opisthotic; iSg., squauiosal. 

 FiO. 1. Platecarpus curtirostris. 

 '2. Clidastes tortor. 

 3. Clidmtts sienoj)), parietal region inferential. 



