106 



M. 



Length of the arch 0.025 



Length of the anterior foot (oblique) — 0. 020 



Length of the ceutnim of the large one 0.060 



Width of the centrum of the large one 0.094 



Width of the neural canal of the large one 0.017 



Ten ribs were recovered. These are slender and rather flatter than in 

 most reptiles, but without the peculiar form characteristic of tortoises and 

 turtles. They are most expanded proximally; the bone spreading into a lam- 

 ina from the tubercular region, extending laterally and proximally some dis- 

 tance beyond the head. The superior plane of this expansion is continuous 

 with that of the rib, and is flat ; the head of the rib therefore turns down- 

 ward and inward from it, to join the vertebra. Now, the extent of the inner 

 part of the lamina is such that, were the head articulated to any of the cen- 

 tra discovered, the laminae would interfere or overlap. They may, therefore, 

 have been articulated to diapophyses. The expansions are serrato-digitate 

 on the margins, and exhibit radiating grooves and ridges in some places on 

 the superior aspect. The lengths of these ribs are not so great as the pro- 

 portions of some of the other bones would indicate. 



Measurements. 



M. 



Length of "No. VI "(16 inches) 0.510 



Width at the head 0.140 



Width of the head 0.040 



Width at the middle 0.055 



Width at the extremity 0.040 



Length of "No. II" 0.300 



Widthof "No. II "just below the head 0.100 



Width at the middle 0.037 



Lengthof "No. IX" 0.380 



Length proximal to the head 0. 060 



Width at the middle 0.080 



In the rib "No. II," the head is turned obliquely to one side, indicating 

 that the rib diverged at a strong angle from the vertebral column ; in fact, not 

 more than one of 45°. This is, then, an anterior or posterior rib ; probably 

 the latter, since the shell is usually expanded chiefly in that direction. All 

 the ribs are flat above, and convex inferiorly. 



Both sides of the scapular arch are complete, except the sutural portions 

 of the coracoid and scapula of one side. The scapula and procoracoid make a 

 very open angle with each other, both being stout; the scapula the longer, 

 with grooved sculpture at its j^roximal end. The procoracoid is a little the 

 shorter. The glenoid cavity and coracoid suture are almost sessile at the 



