PLATE XXTII. 
Ichthyosaurus. 
Cranial and vertebral characters. 
Fig. 
1. Skull, lacking end of snout, upper view {Ich. longifrons, Ow.). 
2. Centrum of atlas vertebra, front view (ib.). 
3. Ib. upper view (ib.). 
4. Ib. back view (ib.). 
5. Atlas and axis vertebrae, side view (ib.). 
6. Atlas, axis, and third vertebrae, side view {Ich latifrons). 
Pigs. 1 — 5 are from the Upper Lias. 
Pig. 6 is from the Lower Lias. 
(All the figures are of the natural size.) 
