BULLFROG AS TYPICAL VERTEBRATE ANIMAL 



87 



From the ventro-aiiterior end of the scapula two bones extend to the 

 mid-ventral line of the body and would meet their fellows from the op- 

 posite side except that the narrow epicoracoid cartilage intervenes. 

 The anterior of these two bars is the clavicle and the posterior one 

 the coracoid. At the junction of coracoid and scapula a depression is 

 formed, known as the glenoid fossa, into which the forelimb articu- 

 lates. The ventral sternum is separated into two portions by the 

 pectoral girdle. The anterior portion is composed of a bone, the 

 omosternum, to which is attached anteriorly a rounded plate of car- 

 tilage, the episternum. The posterior portion is composed of a bone, 

 the sternum proper, and a rounded cartilage, the xiphisternum, which 

 has a notch at its posterior margin through which the abdominal vein 

 runs as it leaves the body wall. 



8^ vertebra 



Sacral 



diapophyses 

 cyfmarical 



Ilium 



Urostyle 



Ac€t<abul(^/D 



- -hchium 

 Fig. 28. — Pelvic girdle of bullfrog, dorsal view. 



The pelvic girdle furnishes a place of attachment and support for 

 the hindlimbs. Each half of the pelvic girdle is composed of three 

 bones, the ilium, ischium, and pubis. The more slender ilium is at- 

 tached anteriorly to the transverse process of the ninth vertebra, and 

 posteriorly it fuses with the pubis and ischium, forming a dishlike 

 concavity, the acetabulum, which receives the hindlimb. The pubis 

 is ventral to this point of fusion, and the ischium is posterior. 



The forelimbs join the body by a ball and socket joint at the 

 glenoid cavity in the pectoral girdle. The large bone which makes 

 this articulation is the humerus. The succeeding bone of the forearm 

 is the radio-ulna, a fusion of two originally distinct bones. The 

 wrist, which follows, contains six carpal bones arranged in two rows. 

 Each hand, or manus, contains four metacarpals following the carpals, 

 and distal to these are four complete digits and an exceedingly small 



