PLATE XXIII. 



Ichthyosaurus. 



Cranial and vertebral characters^ 

 Fig. 



1. Skull, lackiDg end of snout, upper view (Ich. longifrons, Ow.). 



2. Centrum of atlas vertebra, front view (ib.). 



3. Ib. upper view (ib.). 

 4 # lb. back view (ib.). 



5. Atlas and axis vertebras, side view (ib.). 



6. Atlas, axis, and third vertebras, side view {Ich latifrons). 



Figs. 1 — 5 are from the Upper Lias. 

 Fig. 6 is from the Lower Lias. 



(All the figures are of the natural size.) 



