Glass B. Amphihia. 



395 



Tlie shoulder girdle of tlie Urodela is represented by 

 a cartilaginous arcli on either side^ in wMch two regions are dis- 

 tinguislied, one dorsal the other ventral, is the glenoid for the arm. 

 The dorsal portion, the scapula, is narrower than the ventral, 

 the coracoid, which partially overlaps its fellow of the other 

 side. The lower part of the scapula is ossified to a varying extent, 

 the ossification often reaches into the coracoid region, but the upper 

 and lower portions of the girdle remain cartilaginous (Fig. 321). In 

 the Anura (Fig. 322), the coracoid is perforated by a large 

 foramen, and thus separated into anterior and posterior portions, the 

 latter ossified, the former not ossified, but covered by a membrane 

 bone, the clavicle; the right and left coracoids either overlap or 



Pig. 321. 



Fig. 322. 



Fig. 321. Sterniim and shoulder girdle of a Salamander, si stemnm- 

 'CO coracoid, 8c scapula. 



Fig. 322. The same parts of a Fr og . st sternum, ep omostemum, co posterior region 

 of coracoid, sc lower portion of scapula, sc' upper portion of the same, cl claTiele. The 

 •cartilaginous parts in this and the preceding figure dotted. — After Eoker. 



fit close together in the median line as in the Frog.* The scapula in 

 the Anura is divided into upper and lower parts, both ossified, but the 

 upper only partially. The fore limb consists of the same chief 

 parts as in the higher Vertebrata. The carpus, especially in the 

 Anura, usually conforms closely to the typical arrangement. In 

 ■extant Amphibia there are never more than four fingers; the 

 number of phalanges varies. In the Anura the two bones of the 

 forearm are fused. 



Each half of the pelvis in the Urodela consists of a narrow upper 

 portion, the ilium, and a lower broader part, the ischio-pubi s, 

 which is connected medianly with its fellow, and in which there is 



* In some Anura (e.g., the Frog) there is, in the middle line, anterior to the coracoid, 

 a special, partly-ossified cartilage, which has been termed the episternum, 

 although it has no connection with the sternum, and although the episternum of other 

 Vertebrata is purely membrane bone. It is probably to be regarded as a special 

 <levelopraent of the coracoid. 



