220 THE ANATOMY OF VERTBBRATED ANIMALS. 



the portio dura, on the upper part of the posterior face of the 

 quadrate bone, represents the stylohyal, or proximal end of 

 the hyoidean arch. 



The pectoral arch has no clavicle, and the coracoid has no 

 distinct epicoraooidal element, nor any fontanelle. The carpus 

 consists proximally of two elongated and somewhat hour-glass- 

 shaped bones, articulated respectively with the radius and the 

 ulna. The radial is the larger, and is partially articulated 

 with the ulna. Behind these, and directed transversely, lies 

 another curved ossification, the upper concave face of which 

 articulates with the ulna. It is united with the latter bone 

 on the one hand, and with the fifth metacarpal, on the other, 

 by strong ligaments, and represents a pisiform bone. Distally, 

 there lies on the ulnar side the so-called lenticular bone, an 

 oval ossicle interposed between the ulnar proximal carpal and 

 the second, third, fourth, and iifth metacarpals, the last three 

 of which it supports altogether. On the radial side, a disk 

 of cartilage, which never becomes completely ossified, is con- 

 nected by ligament with the lenticulare, and is interposed 

 between the radial proximal bone and the head of the meta- 

 carpal of the poUex. From the ulnar side of the head of this 

 bone a cartilaginous ligamentous band proceeds, over the head 

 of the secoad metacarpal, to the radial side of the lenticulare. 



The three radial digits are much stronger than the two 

 ulnar, and the numbers of the phalanges are 2, 3, 4, 4, 3, 

 counting from the radial to the ulnar side. 



The pelvis (Fig. 78, C) possesses large ilia, which are firmly 

 united with the expanded ends of the strong ribs of the sacrum. 

 The ischium unites with its fellow in a median ventral symphysis, 

 and, with the ilium, forms almost the whole of the acetabulum. 



The pubcs take hardly any share in the formation of the 

 latter cavity in the adult. Their axes are directed forward 

 and inward, and they coalesce in the middle line ; but as the 

 inner, or median, moietj^ of each pubis remains cartilaginous, 

 or imperfectly ossified, the bones, in imperfectly prepared 

 skeletons, appear as if they formed no symphysis. 



The tarsus presents, proximally, an astragalo-navicular 

 bone and a calcaneum, which are less closely united than in 

 the Lizards. The latter bone has a large calcaneal process on 

 Its posterior face, the Crocodile being the only Sauropsid verte- 

 brate in which ijuoh a process is developed (Fig. 78, C. Ca.). 



Two rounded c>'«tal tarsal bones, of which the fibular is 

 much the larger, lie •^.'^ween the calcaneum and the third, 

 fourth, and rudimentaiy ti.''t-li, metatarsals. A thin plate of 



