a new Fossil Animal . 
569 
the back part of the jaw, and broader and flatter at their posterior 
extremity, where they underlie the orbit, and are slightly curved to 
fit them for their situation. In the roof of the mouth, the maxil- 
lary bones, receding from each other as they advance towards the 
posterior parts, exhibit, (as seen in fig. 3 & 12, plate 40.) the 
palatals, e y e 9 which closely resemble those of the crocodile, but are 
still longer and narrower. 
Between the posterior terminations of the palatal and maxillary 
bones, is an opening, as in crocodiles, but more elongated and nar- 
row ; this opening in the crocodile is surrounded on the posterior 
side by the pterygoid processes, ff y and a peculiar bone, d , which 
may be considered as an external pterygoid process intervening be- 
tween the preceding and the maxillary bone on either side. This 
structure, considered I believe, as peculiar to these animals, is also 
to be observed in the Ichthyosaurus, where the peculiar bone, d , 
will be seen resting against the inside of the termination of the max- 
illary, and extending in a long process to the hinder extremity of 
the head. Of the pterygoid processes ff traces only have been 
as yet discovered, too much broken and distorted for representation, 
but quite sufficient to shew that they nearly agreed with those of 
the crocodile. 
Having thus described such of the bones as occur in the roof 
of the mouth, we proceed to those which occupy the external part 
of the face. The nasal bones, k y k , are placed as in the crocodile. 
Between the nasal bones and the posterior extremity of the maxil- 
lary bones, b y b y lie the lacrymal bones, /, i ; these form the anterior 
margin of the orbit in its lower part ; in front of these bones are 
placed the oval openings before alluded to as is generally to be ob- 
served in all the skulls of this animal yet found, with a single excep- 
tion, which at first (and as we still think with much probability) 
4 c 2 
