FOSSIL REPTILES. 353 



the upper one extends over a good part of the superciliary 

 arcade. This appeared to M. Cuvier to be the anterior 

 frontal. The other, which is smaller, he thought might be 

 the lachrymal, but could discern no lachrymal foramen. 



The two nasals re-ascend between the anterior frontals as 

 far as the principal frontals, to which they are articulated by a 

 notched suture, which varies in direction according to the 

 species. 



The principal frontals are placed, as usual, on the middle 

 of the interval of the orbits, but it does not appear that they 

 came as far as their upper edge. 



The posterior frontals proceed along the superciliary arch, 

 and the external edge of the principal frontals, to join the 

 anterior. They also form all this posterior edge of the orbit in 

 descending to join the jugal bone. This last is slender. It is 

 placed obliquely on the maxillary to form all the lower edge of 

 the orbit, and remounts a little behind to join the posterior 

 frontal, with which it closes the frame of the orbit. But this 

 ascending part is not considerable, so that the emargination 

 exhibited by the zygoma underneath, in the lizards, is less in 

 the ichthyosaurus^ 



A broad bone behind the orbit is peculiar to the ichthyo- 

 saurus, and distinguishes it from the lizards. This bone arti 

 cuiates with the posterior edge of the posterior frontal, and of 

 the jugal, and proceeds from its other extremity to take part 

 in the articular face which bears the lower jaw. The bone 

 which joins the rest of this articular face is placed more 

 within than the preceding, and suspended to the mastoid and 

 the lateral occipital. These two bones, M. Cuvier thinks, are 

 the temporal and tympanic. 



The temporal, in its form, much resembles that of the 

 lizards, only that it is articulated by a higher line to the pos- 

 terior frontal and the jugal bones. But its peculiar character 

 is its descending like that of the crocodile, as far as the articu- 

 lation ; but, though articulating with the posterior frontal, it 



2 A 



