392 



ICHTHYOSAURIA. 



FIG. 218. Diagrams illustrating the principal characters of Ichthyosaurus (from S. 

 ward). A side, B dorsal, C ventral, D posterior view of the skull of Ichthyosaurus 



Wood 



. , , , Ichthyosaurus longi- 



jrons, L. Jurassic (U. Lias), ag angular ; art articular ; b.occ basioccipital ; b.s basisphenoid ; 

 d dentary ; ex.occ exoccipital ; f.m. foramen magnum ; fr frontal ; i.pt interpterygoid 

 vacuity ; / jugal ; la lacrymal ; mx maxilla ; na nasal ; nar external nares ; occ.c occipital 

 condyle ; op.o opisthotic ; pa parietal ; pas parasphenoid ; pin pineal (parietal) foramen ; 

 pi palatine ; pmx premaxilla ; prf prefrontal ; pt pterygoid ; pt f postfrontal ; pt.nar posterior 

 nares : pto postorbital ; qj quadratojugul ; qu quadrate ; s.ag surangular ; scl. sclerotic plates ; 

 s.occ supraoccipital ; spl splenial ; sq squamosal ; s.t supratemporal (prosquamosal) ; s,t.f 



