32 



ICHTHYOPTERYGIA. 



rostrum very long and 



Ichthyosaurus entheciodon, Hulke \ 



Typically of medium size. Cranial 

 slender ; teeth small, with bulbous roots. Vertebras (if No. 46473 e 

 be rightly referred) with the cupping of the posterior face of the 

 centra confined to the central region, and the costal tubercles of the 

 dorsals very small. Inner border of coracoids greatly elongated. 

 Femur (fig. 16) long, with its trochanteric and opposite ridges 

 moderately developed, so that the lateral surface of the proximal 



Fig. 16. 



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

 femur ; from the Kimeridge Clay of Weymouth. \ a, trochanteric 

 ridge , t, tibial, /, fibular facet. 



portion is narrower than the dorsal. Limbs relatively very small ; 

 the humerus and femur in the type skeleton being not larger than 

 in I. latifrons {infra, p. 89), where the vertebral centra are only 

 half the size of those of the present form ; whether this form is 

 really distinct from the preceding species remains to be proved. 

 Hob. Europe (England). 



46497. Slab showing the right lateral aspect of the nearly entire 

 (Fig.) skeleton; from the Kimeridge Clay (Upper Jurassic) of 

 Kimeridge Bay, Dorsetshire. Described and figured by 

 Hulke in the ' Quart. Journ. Geol. Soc' vol. xxvii. p. 440, 

 pi. xvii. This specimen is in rather bad preservation ; 

 the extremity of the caudal region is wanting, and of the 

 limbs only the proximal portions remain. The pentagonal 

 contour of the cervical centra can be distinctly seen where 

 the vertebrae are partially displaced. The dorsal aspect of 

 the humerus shows a strong trochanteric ridge ; while 

 both this bone and the femur articulate distally with the 



1 Quart. Journ. Geol. Soc. vol. xxvii. pp. 30, 440 (1871)— amended. In 

 vol. xxvi. p. 174 (1870) the name Enthekiodon was applied in a generic sense 

 to teeth of this species. 



