(b) The more slender clavicles anterior to them, both extending from the base of the arm on each side towards the centre of the body.

(c) The sternum, consisting of a median row of cartilages which are believed to be derived from the shoulder girdle. It does not, therefore, correspond to, or is not homologous with, the sternum of the Pigeon or the Rabbit, which is derived from the ribs. The sternum consists of the following parts:

(i) The two epicoracoids consisting of cartilage.

(ii) The metasternum which is broad and consists of cartilage only.

Fig. 4.—Pectoral Girdle of Xenopus and Rana.

[In the Frog the sternum is composed of the following parts:—

(i) The omosternum consisting of two parts, an anterior cartilaginous part (sometimes called the omosternum) and a posterior bony part (sometimes called the episternum).

(ii) The two epicoracoids consisting of cartilage.

(iii) The metasternum consisting of two parts, an anterior bony part (sometimes called the sternum) and a posterior cartilaginous part (sometimes called the xiphisternum).]