MKRRIA.M: TIMASSir 1C! ITU Y( )SA I RIA. ]:>,] 



DKI , i > 1 1 1 \ < ISA r ars Merriam. 



ji/rrhii Merriam, Univ. Calif. Publ. (icol.. vol. 3, p. 89, pis. 5, (i. and 7. 

 Ddphinosaurus Mi>rriani, Ainer. Jour. Sc., vol. 19, p. 24. fijr. :i. .Ian., 1905. 



Vertebral centra relatively much elongated, length of dorsal centra equal- 

 ing one-half to three-fourths of their height. Neural arches of dorsal verte- 

 brae much compressed laterally, though low lateral ridges or ribs are present. 

 Scapula broad sickle-shaped, and without anterior notch or hook. Coracoid 

 not pedunculate, with a well-marked anterior notch. Humerus narrower medi- 

 ally than in Shastasaurus. Epipodial elements of anterior limb both relatively 

 elongated, and with median constriction. The genus ranges through the 

 greater part of the lower or shaly horizon of the Hosselkus Limestone. 



In the first study of D. perrini, the type species of this genus, the vertebrae 

 were distinguished from those of the other forms referred to Shastasaurus by 

 their extraordinary anteroposterior diameter. The typical species was, how- 

 ever, referred to the genus Shastasaurus, other distinguishing characters not 

 being recognized owing to the fact that excepting ribs and vertebrae nearly 

 all of the parts present in this species were lacking in the known species of 

 Shastasaurus. More recent discoveries have made known nearly the whole of 

 the skeleton of this form excepting the distal portions of the paddles. While 

 the skeletal structure obviously represents the shastasaurian group, it is dis- 

 tinguished from that of the typical species of Shastasaurus by several impor- 

 tant characters other than those of the vertebrae. Only one species, D. per- 

 rini, is recognized. 



DELPHINOSAUKUS PERRINI Merriam. 



Shastasaurus perrini Merriam, Univ. Calif. Publ. Geol., vol. 3, p. 89. 

 Delphinosaurus perrini Merriam,. Amer. Jour. Sc., vol. 19, p. 24. Jan., 1905. 



Type specimen no. 9119, Univ. Calif. Col. Vert. Palae. Since the discovery 

 and description of the type material three valuable specimens representing this 

 species have been obtained. A considerable number of more fragmentary 

 specimens indicate the geologic range of the species. 



No. 10998 (pi. 7, fig. 3), a small specimen about two metres long, represents 

 a large part of the skeleton, extending from the anterior region of the skull 

 to the end of the tail. This specimen is somewhat smaller than the type of 

 D. perrini, and the vertebral centra are slightly less elongated in proportion 

 to their height, but the resemblance to that species is in general very close. 

 In this specimen the vertebral column includes 115 centra and appears to be 

 nearly complete. About 75 of the centra are in the caudal region, which con- 

 stitutes nearly one-half of the length of the column. The remaining 40 verte- 



