102 



University of California. 



Vol. 3 



MEASUREMENTS OF A RIB. 



Length of portion of proximal surface of head below 



constriction .... 31 mm. 



Breadth of lower surface 20 



Length of portion above constriction 32 



Breadth of portion above constriction 14 



Height of shaft 90 mm. from proximal end 24 



Width of flattened superior surface 19 



The two limb hones are like the notched elements on the 

 anterior borders of the limbs of the longipinnate Ichthyosauria. 

 Excepting on the notched side, their margins show a regularly 

 rounded outline and it is, therefore, not probable that they 

 represent either the radius or the tibia, but were situated in the 

 metapodial or phalangial segments. The perfect specimen is 

 represented by fig. 5, PI. 14. The following are their 

 dimensions : 



Perfect Fragmentary 

 specimen. specimen. 



Greatest transverse diameter 85 mm. 



Greatest axial diameter 67 74 mm. 



Greatest thickness 35 37 



Depth of notch 20 25 



Shastasaurus pacificus. Merriam. 



PL. 14, PIGS. 1 AND 2. 

 Shastasaurus pacificus Merriam. Am. Jour. Sci. Vol. 4, 1895, p. 56. 



The type species of the genus Shastasaurus was based on a 

 series of eight vertebrae with several fragments of ribs and two 

 arch bones, one of which was very fragmentary, the other being 

 practically perfect. The vertebrae were recognized as pre-caudals, 

 and, being associated with what were supposed to be certainly 

 coracoids, they were described as doubtful anterior dorsals. A 

 re-examination of the type shows the vertebra? to have been 

 without chevrons, while the diapophyses occupy the same posi- 

 tion as those near the pelvic arch, so that they may be consid- 

 ered as posterior dorsals. 



The elements which were taken to be coracoids (PI. 14, fig. 

 2) are very different from both the coracoid and the scapula of 

 the two species in which these bones are known. This difference 

 appears in the general outlines, and more particularly in the form 

 of the proximal end (text fig. 1), which is very characteristic on 



