MKKKIAM: TK I. \SS1C K '! IT] I VOSAI'KIA. 145 



vertebral centrum is in these forms quite different from that of the typical 

 Ichthyosaurus. 



From S. cnrci/i this species differs in having longer vertebral centra and 

 very much longer neural vertebral spines, with anteroposteriorly grooved in- 

 stead of strongly convex terminal faces of the neural spines. The upper ends 

 of the neural spines of the middle dorsal region arc also much thicker than 

 the middle portion of the arch in S. 

 cfiir/ji. In V. <tltixj>inuK a tendency to 

 thicken the upper portion of the neural 

 spines appears, but it is not developed 

 as far as in S. carci/i. 



Two paddle elements occurring with 

 the type specimen of this species both 

 show sharp marginal notches (fig. 149) 

 such as are not seen in any discoidal 

 limb bones of S. oxmoHti. The periphe- 



1")1 t'-lCP in these elements IS cmic-ive -Illd Fig ' 149 ' Klla><tlls <" trvs *P* Merriam. Margi- 

 nal element from mesopodial, metapodial, or 

 HlUch roughened. phalangcal region, X %. 



SHASTASAIIRUS CAREYI Merriam. 

 x careiji Merriam, Univ. Calif. Publ. Gcol., vol. 3, p. 98, pi. 14, figs. 3 and 4. 



Vertebral centra relatively high and short. Neural spines of dorsal verte- 

 brae considerably thickened distaily. Limb elements more abbreviated than 

 in other species. Radivis relatively large. 



The type specimen (no. 9075, Univ. Calif. Col. Vert. Palae.) of this species 

 consisted of two very large vertebrae and some rib fragments from the ante- 

 rior dorsal or posterior cervical region. The diapophyses are short, and rudi- 

 mentary parapophyses are present below them. The centra are relatively short 

 anteroposteriorly. The dimensions of the centra in this specimen indicate that 

 this form approached the size of the largest known species in the genus Ichthy- 

 osaurus. 



MEASUREMENTS, NO. 9075. 



Width of vertebral centrum from anterior dorsal or posterior cervical 



region 180 mm. 



Height of centrum a!60 



Anteroposterior diameter of centrum 60 



a Approximate. 



