EXPLANATION OF PLATE 6. 



Shastasaurus perrini n. sp. 



All figures are from the type specimen. 



Fig. 1. — Posterior arch and limbs, showing position of elements in the 

 matrix. Ir, right ilium; II, left ilium; Isr, right ischium: 

 Isl, left ischium; Pr, right pubis; PI, left pubis; Fr, right 

 femur; Fl, left femur. One-third natural size. 



Fig. 2. — Right femur, side view. Three-fourths natural size. 



Fig. 3. — Right femur, proximal end, showing the position of its longer trans- 

 verse diameter with reference to that of the somewhat damaged 

 distal end. Three-fourths natural size. 



Fig. 4. — Left posterior limb. Fb, fibula; T, tibia. The small ossicle 

 between the tibia and femur is probably a loose phalanx like 

 two near the proximal end of PI in figure one. The fragment 

 of an ossicle shown in outline between the tibia and fibula 

 possibly represents the intermedium. Three -fourths natural size. 



