142 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA. 



Posterior Limb. 



Femur, length 132 mm. 



Femur, width of proximal end 78 



Femur, greatest diameter of proximal end 84 



Femur, width of distal end 117 



Tibia, length 96 



Tibia, width of proximal end 92 



Tibia, width of narrowest portion of shaft 66 



Tibia, width of distal end 108 



Fibula, length 94 



Fibula, width of proximal end 41 



Fibula, width of distal end 86 



Of the skull only the most posterior portion of the cranium and of the lower 

 jaw are present in specimen 9081. In the posterior parietal region the rela- 

 tions of the parietals are seen for the first time in Shastasaurus, the posterior 

 arms of the parietals extending backward behind the parietal arch of the squa- 

 mosal, as in Cymbospondylus and Baptanodon. 



The relations of the temporal, supratemporal, postorbital and quadrate are 

 distinctly shown, and are much as in S. alexandrae. The articular face of the 

 quadrate shows a weak transverse groove. 



The form of the basioccipital appears to be different from that in Ichthyo- 

 saurus or Baptanodon. The inferior side of this element is produced as two 

 prominent hypapophyses not unlike the corresponding prominences in Cym- 

 bospondylus or in the Mosasauria. The posterior articular face is strongly 

 convex. 



SHASTASAURUS ALEXANDRAE Merriam. 

 Shastasaurus alexandrae Merriam, Univ. Calif. Publ. Geol., vol. 3, p. 96, pis. 12 and 13. 



Vertebral centra much as in S. osmonti, but much longer anteroposteriorly 

 than in S. careyi. Anterior cervical ribs double-headed; posterior cervical or 

 anterior dorsal ribs single-headed. Elements of the pectoral arch and anterior 

 limb much broader and thinner, and anterior notch of the humerus much wider 

 than in S. osmonti. 



Type specimen, no. 9017, Univ. Calif. Col. Vert. Palae., from the upper part 

 of the Trachyceras Beds of the Hosselkus Limestone, one-quarter of a mile 

 south of Smith's Cove, Brock Mountain, between Squaw Creek and Pit River, 

 Shasta County, California. Fragmentary material apparently belonging to 

 this species has been found at other localities in this region. 



The type specimen of this species represents an individual of nearly the 

 same size as the type of S. osmonti, but the cervical and anterior dorsal verte- 



