42 



ICHTHYOPTEEYGIA.. 



with moderately deep cups; neural spines of dorsal and cervical 

 vertebras very tall, their height exceeding twice the vertical diameter 

 of the centra. Number of vertebras generally about 140. Pectoral 

 paddle (fig. 20) very broad, and usually about double the size of 

 pelvic. There may be eight longitudinal rows of bones in middle of 

 former, and six in latter. In pelvic paddle (fig. 20) anterior border 

 of tibiale and succeeding tarsals of second row entire, and also the 

 same border of anterior row of bones in pectoral paddle. Four 



Pig. 19. 



Ichthyosaurus communis. — Tooth 



bones in third transverse row of pelvic paddle. Yascular foramina 

 in centre of bones of paddles very minute and indistinct. Slight 

 variations occur in the form of the paddles of different individuals 

 included under the present specific heading ; but these variations 

 can scarcely be regarded as of more than racial importance. This 

 species attained dimensions somewhat inferior to 1. hnchiodon. 



In the case of young skeletons and imperfect skulls, it is frequently 

 difficult to distinguish between this species and /. intermedins. 



Hah. Europe (England). 



41849. Slab showing the left aspect of a medium-sized skeleton, 

 {Fig.) wanting the greater part of the caudal region ; from the 

 Lower Lias of Lyme-Regis, Dorsetshire. The bones of 

 the brain-case are much crushed, but the rostrum is well 

 preserved, and considerably exceeds twice the longer 

 diameter of the orbit. The dorsal aspect of the coracoids 



