SKELETON. 



377 



The pectoral girdle consists of a scapula with a dorsal cartila- 

 ginous suprascapula margin, and of a coracoid without a fenestra. 

 The coracoid articulates with the sternum. There is no clavicle, 

 but an interclavicle lies on the sternum. There are five digits 

 in the manus. 



The carpus consists of six pieces : a radiale, an ulnare which articulates 

 with the pisiform and radiale, but does not reach the ulna, and a pisiform 

 in the proximal row ; in the distal row there is a piece of cartilage repre- 

 senting carpale 1 and 2, and a bone (lenticular) representing carpale 3, 

 •i, and 5. In addition there is a small cartilaginous centrale on the distal 

 surface of the radiale. The three radial digits are stronger than the two 

 ulnar and bear claws. 



Fig. 206.— Biagram 

 of the passages 

 connecting (the 

 t.ympanic cavities 

 witli the pharynx 

 in Crocodilus (after 

 Owen,from Gegen- 

 baur). n valve at 

 the pharyngeal 

 opening ; o median 

 canal, whicli 

 divides into an 

 anterior q and a 

 posterior r ; for 

 «, t, p see text. 



Fig. 207. — Pelvis and sacrum of an alligator 

 {Caiman latirostris) x \ (after Reynolds). 1 

 ilium ; 2 ischium ; 3 forward process of ischium ; 



4 pubis ; 5 acetabular foramen : « neural 

 spines of sacral vertebrae ; 7 symphysis ischii;; 



5 prezygapophysis. 



In the pelvis (Fig. 207) the ilia are attached to the two sacral 

 ribs ; the ischium is large and is joined to its fellow in a ventral 

 symphysis by synchondrosis. The pubis is directed forwards 

 and is excluded from the acetabulum by a forward process of the 

 ischium. The ventral end of the pubis remains cartilaginous, 

 and extends forwards as an epipubis. In front the two epipubes 

 are separate, but behind they are united by a broad and strong 

 ligamentous band. There are four digits in the pes, Xo. 5 being 

 absent. 



It is sometimes stated that there is no pubic or ischiadic symphysis. 

 But though it is true that the hones do not meet and appear separate in 



