EXPLANATION OF THE PLATES. 



Dismemberments of the occipital bone. 



q. Superior occipital. 



r. Inferior occipital. 



J s. Lateral occipitals. 



I *t. Basilar portion of the sphenoid. 1 ■•,,., : 



^,, „ J- * iu 11 * • f JNot visible in these specimens. 



[_ *l . Process corresponding to the sella turcica, j ^ 



N.B. M. Cuvier seems (for his notice is very slight) to have considered these 

 last two bones, together with the internal pterygoid, and the bones marked g, 

 as forming in the crocodile a single and united sphenoid. But in the com- 

 mon Nilotic crocodile they are certainly distinct bones, the sutures between 

 them being very evident. These sutures are clearly exhibited in a specimen 

 in my possession, and maybe traced in the figure given by Scarpa (de Au- 

 ditu) ; they closely correspond to the similar parts in the turtle. — See Bo- 

 jani, Anatome Testudinis. 



Bones of the lower jaw. 



f u. Dental. 

 I V. Angular, 

 j X. Coronoid. 

 1 t/. Articular. 



z. Crescent-shaped. 



Sf. Opercular. 



The letters above given, having been adopted merely for the convenience of refe- 

 rence to M. Cuvier's plates of the osteology of the crocodile, are not systemati- 

 cally disposed. The transpositions which a more natural arrangement would render 

 necessary are indicated in the foregoing list. 



Particular Figures. 



Plate XV. 



Illustrates the dentition of Ichthyosaurus. 



Figs. 1 & 2 show the succession of the new teeth in the crocodile : see p. 106. 



Fig. 3. The same in the fossil Saurian of Maestricht ; selected as an example of the 

 common lacertian type : page 106. 



Figs. 4, b, 6. The same in the Ichthyosaurus : pp. 106, 107. 



The following figures illustrate the teeth of the different species. 

 Fig. 7. Tooth of Ichthyosaurus platyodon : page 108. 



8. > 1, communis, . . . . ibid. 



9. 1, intermedins, . . . . ibid. 



10. 1, tenuirostris, . . . . ibid. 



Fig. 11. Probably a tooth of Plesiosaur us : p. 120. 



