214 THE ANATOMY OF VEETEBEATED ANIMALS. 



backwards, into a low recurved plate. This part appears to 

 repi-esent the proper body of the scapula in other Reptiles, 

 while the horizontal prolongation answers to that pre- 

 glenoidal process of the scapula, which extends forwards and 

 inwards as a free bony bar in many Lacertilia — for example, 

 Iguana. 



In well-preserved specimens, a broad hoop of substance 

 (Fig. 68, E, a), which seems to have been but imperfectly 

 ossified, extends across the middle line of the body, from 

 the preglenoidal process of one scapula to that of the 

 other, and is continued backwai'ds in the middle line, to 

 the junction of the two coracoids. This corresponds very 

 nearly in form and position to the epicoracoidal ossifica- 

 tions of the Lacertilia, combined with the clavicles and 

 interclavicles ; but I have never been able to detect any 

 distinct clavicular, or interclavicular, elements in any Plesio- 

 saurus, though they appear to have been well developed in 

 Nothosaurus. 



The humerus is a stout bone — prismatic, and with a 

 rounded head at its proximal end, flattened and broad 

 distally. (Fig. 68, B.) Its anterior margin is nearly straight, 

 or even slightly convex, while the posterior is concave. 

 Distally, it presents two facets, meeting at an angle, with 

 which the broad and short radius and ulna articulate. The 

 ulna differs in shape from the radius, being convex pos- 

 teriorly, and concave in front. The two bones are of equal 

 length, and much shorter than the humerus. There are 

 six rounded carpal bones,* arranged in two rows ; and to 

 these succeed five digits, composed of metacarpals and 

 phalanges, which are elongated and constricted in the 

 middle. The middle digits have numerous phalanges. 



The pelvic arch has very large dimensions, in correspon- 

 dence with the size of the hind limb, which is usually longer 

 than the fore limb. (Fig. 68, F and D.) The ilium is a 



* It may be a question whe- tarsus, or to metacarpus and 



ther the fourth distal bone in the metatarsus; or whether it is 



carpus and tarsus (Fig. 68, B formed by the confluence of ele- 



and D) belongs to carpus and ments belonging to both regions. 



