,892 



ICHTHYOSAURIA. 



Fig. 218. — Diagrams illustrating the principal characters of Ichthyosaunis (from S. Wood 

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

 irons, L. Jurassic (U. Lias), ug angular ; art articular ; b.occ basloccipital ; b.s basisphenoid ; 

 d dentary ; ex.occ exoccipital ; j.m. foramen magnum ; jr frontal ; i.pt interpterygoid 

 vacuity ; j 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 / postfrontal ; pt.var posterior 

 nares : pto postorbital ; gj quadratojugul ; gu quadrate ; s.ag surangular ; scl. sclerotic plates ; 

 s.occ supraoccipital ; spl splenial ; sj squamosal ; s.i supratemporal (prosquamosal) ; s.t.f 



