134 BRITISH FOSSIL REPTILES. 



vertebra3 through the whole spinal column, and establishes another difference' 

 between the Teleosaur and the Gavial, the former having a number of vertebrae- 

 intermediate between the Crocodiles and Gavials, viz. 64, with a special peculiarity 

 in the excess of costal vertebras, as the following formula indicates, viz. 7 cervical, 

 16 dorsal, 3 lumbar, 2 sacral, 36 caudal. 



In all sub-genera of existing Crocodiles, as in the extinct tertiary species, the 

 hind surface of the vertebra is convex, the fore surface concave, except in the 

 atlas and the two sacral vertebrae. 



Cuvier, who had the opportunity of seeing only the annular part (neurapo- 

 physes) of the cervical vertebrse of the Caen Teleosaur, regrets his inabihty to 

 state whether either of the articular extremities of the centrum were convex, or 

 which of them.' The Whitby Teleosaur decides this question, and shows that both 

 articiilar extremities of the vertebrae are slightly concave in the cervical as in the- 

 rest of the vertebral series. 



The atlas in the Teleosaur corresponds essentially with that of the Crocodiles, 

 as is shown by the three main component parts of this bone from a Whitby 

 Teleosaur in Lord Bnniskillen's collection. The hypophysial centrum is a trans- 

 verse quadrilateral piece, smooth and convex below, narrowing like an inverted 

 wedge above, with six articular facets, viz. a concavity in front for the occipital 

 condyle, a flat rougher surface on each side of the upper part for the attachment 

 of the neurapophyses, a posterior facet for the anterior part of the true centrum, 

 or ' odontoid element ' of the axis, and the small surface on each lateral, posterior, 

 and inferior angle for the atlantal ribs. The neurapophyses are pyramidal pro- 

 cesses, with their apices curved towards each other ; they are relatively smaller in 

 proportion to the centrum than in the Crocodiles. 



The general anterior concavity for the reception of the occipital tubercle is 

 formed at its circumference by the hypophysial centrum and neurapophyses of the 

 atlas, and at its middle by the anterior detached odontoid, here evidently the 

 homologue of the atlas in the Ichthyosaurus, the hypophysial centrum of the atlas in 

 the Teleosaur representing the first inverted wedge-shaped bone in the Ichthyo- 

 saur. The spine of the atlas is a large, strong, oblong piece, articulated with the 

 neurapophyses of the atlas, and partly overlapping those of the axis. 



The cervical vertebrjB have strong transverse processes, a parapophysis 

 developed from each side of the centrum, and a diapophysis from the base of each 

 neurapophysis. The postzygapophyses look obliquely downward and outward, the 

 prezygapophyses obliquely upward and inward. The spine is compressed, its base 

 coequal with the whole antero-posterior extent of the nem^apophysis, its height 

 equal to the distance from its base to the diapophysis ; it inclines slightly backward,. 



1 ' Ossem. Fossiles,' 4to, 1824, torn, v, pt. ii, p. 137. 



