FOSSIL REPTILES. 359 



M. Cuvier has seen in three individuals the two anterior 

 horns of the hyoid bone, otherwise the styloid bones, in their 

 place, large, prismatic, and as osseous as any of the other bones. 

 He has even observed between them an osseous disk of greater 

 breadth than length, emarginated behind, which he suspected 

 to be the body of the hyoid. Having seen nothing to announce 

 the existence of bronchial arches, he considers that this animal 

 respired the elastic air, and had neither gills like a fish, nor 

 any bronchial apparatus like the siren or the axolotl. He 

 could, however, discover nothing which appeared a remain of 

 larynx, or windpipe. 



The number of vertebrae in the ichthyosaurus is consider- 

 able. Mr. Conybeare rates it at between eighty and ninety. 

 M. Cuvier possesses an individual which could not have had 

 less than ninety-five. In the fine specimen of Sir Everard 

 Home, the vertebrae amount to seventy- two, at least. 



As much as the ichthyosaurus resembles the lizards in the 

 forms of its osseous head, so much does it differ from them in 

 the conformation of its vertebrae, and in this respect decidedly 

 approaches the fishes and cetacea, as Sir Everard has well 

 remarked. 



It has not the atlas and axis differently formed, but all the 

 vertebrae are nearly alike, as in fish. Their bodies are shaped 

 like the pieces of a draught-board ; that is, the diameter is 

 greater than the axis, sometimes even double or treble. Both 

 faces of their bodies are concave, just as in fishes. 



The annular portion is attached to them on one part and 

 the other, by a face somewhat rough, which takes the whole 

 length of each side of the medullary canal. The adherence 

 must have been weak, for in most cases this annular portion is 

 gone. It was raised above in a compressed spinous apophysis, 

 which, in the commencement of the spine, is pretty nearly the 

 height of the body. These apophyses, placed obliquely, and 

 almost as broad as the bodies, formed, on this part of the spine, 

 almost a continuous crest. That of one vertebra rests its base 



