a new Fossil Animal . 
571 
The only difference in these respects is, that the post-orbital pro- 
cess h'\ h'\ in the Ichthyosaurus, does not, as in the crocodile, 
bend inwards, but meets the jugal r, in the line of the general 
curvature of this part of the face, so that the margin of the orbit 
is nearly of the same curvature throughout, and the jugal bone r, 
in consequence of the lower situation of the eye, is much reduced 
in size. 
We have now arrived at the bones which are behind the orbits 
and over the summit of the cranium, corresponding in situation to 
the parietal bones of other quadrupeds. 
Here again the crocodile has a peculiar structure, this part of 
the head being distinguished by two large oval openings not unlike 
those of the orbits, but rather smaller, which may be called from 
their situation the super-parietal cavities. Between these cavities is 
the bone m , answering to the single parietal of ruminants, the bones 
marked n , considered as answering to portions of the temporal 
bones form their posterior angles, and by uniting with the lateral 
frontals h\ complete the enclosure. 
All these strongly marked characters occur without any material 
deviation in the Ichthyosaurus. 
The last bones of the head we shall describe are those which 
interpose between the jugal c } and the last mentioned bone ( n ), and 
which together with it, are considered as making up the remainder 
of the temporal ; the first of these, 0, which bears at its inferior and 
hinder extremity the condyle for articulation with the lower jaw, 
may be observed placed in the Ichthyosaurus, as in the crocodile, 
namely, extending from the lateral frontal h\ towards n, to a pro- 
cess of which it joins ; p is interposed between this and the jugal 
bone c, and thus completes the enclosure of the temporal fossa, 
which seems to have been narrow in this animal. 
