ICHTHYOSJlTTKID.E. 



15 



This subgroup includes the most specialized forms, and those 

 nearly related to Ophthalmosaurus. 



Ichthyosaurus campylodon, Carter l . 



Of very large dimensions. Skull stout, with elongated rostrum. 

 Teeth (fig. 11) very large and closely approximated, with the 

 crowns slightly curved and very coarsely fluted. Centra of ver- 

 tebrae of moderate length, with the cupping of the terminal faces 

 moderately deep, and a distinct deeper pit in the centre of the an- 

 terior face. Femur (fig. 10) very short, with its trochanteric and 



Fig. 10. 



Ichthyosaurus campylodon. — Dorsal, postaxial, and distal aspects of the right 

 femur; from the Cretaceous (?Grault) of Russia. -§. a, trochanteric ridge ; 

 t, tibial, f, fibular facet. {After Kiprijanoff.) 



opposite ridges enormously developed, so as to make the lateral 

 surfaces of the proximal portion wider than the dorsal. 



This species was originally described from the Lower Chalk of 

 Cambridgeshire on the evidence of jaws and teeth. Teeth of similar 

 type are found from the Upper Chalk to the Gault, and in the 

 absence of any evidence to the contrary are referred to the same 

 species, although it is quite probable that they may belong to more 

 than one species. The specimens of humerus and femur (fig. 10) 

 associated with teeth of this type from the Cretaceous of Russia, 

 figured by Kiprijanoff 2 , show the two distal facets characteristic of 

 Ichthyosaurus, and have a strongly developed trochanteric ridge. 

 An associated radius, figured by the same writer 3 , closely resembles 

 fig. 8, having the entire anterior border and transversely elongated 

 contour characteristic of the present group; while an ulna 4 attached 

 to one specimen of the humerus is also of the characteristic sub- 



1 Rep. Brit. Assoc, for 1845,— Trans, of Sections, p. fiO (1846). 



2 Mem. Ac. Imp. St. Petersbourg, vol. xxviii. art. 8, pis. xiv., xv. (1881). 



3 Ibid. pi. xiv. fig. 3. 4 Ibid. fig. 1, 



