18 



3. The pectoral girdle and sternum. (To be examined in the second frog after 



the muscles have been dissected.) 

 a. The sternum note from before backwards. 



(a) The episternum, a small circular plate of cartilage. 



(6) The narrow bony omosternum. 



(c) The epicoracoids, consisting of a piece of cartilage at each side of 



the middle line between the coracoids. 

 {d) The sternum proper, consisting externally of bone and internally 



of cartilage, 

 (e) The large bifid cartilaginous xiphisternum. 

 h. The pectoral girdle. Observe — 



(a) The prsecoracoid, a narrow bar of cartilage, extending from the 



sternum to the anterior margin of the scapula. 

 (&) The post-coracoid, a flattened bone extending from the sternum 



to the posterior margin of the scapula and entering into the 



formation of the glenoid cavity. 



(c) The clavicle (a membrane bone) ensheathing the anterior margin 



of the prsecoracoid. 



(d) The scapula, a short expanded bony plate which forms the upper 



portion of the glenoid cavity. 



(e) The suprascapula, a large thin plate of cartilage in which a 



limited amount of osseous and calcareous matter is usually 



deposited. 

 Make a drawing (2 nat. size) showing the sternum and pectoral girdle, 

 colouring the cartilage blue and the clavicle red, in order to dis- 

 tinguish it from the cartilage bones. 



4. The fore-limb. 



Eemove the muscles and examine the bones, and make a sketch (2 nat. size) 

 showing — 



(a) The humerus with a rounded head, deltoid and condylar ridges, and 



a spheroidal articular surface for the radio-ulna. 

 (6) The radio-ulna concave and simple above, with an olecranon process, 



but divided below and presenting three facets for the carpals. 

 (c) The six carpals — radiale, ulnare, centrale, and three distalia. 

 {d) The metacarpals and phalanges of the digits — ^the 1st digit (poUex) 



having no phalanges ; the II. and III. digits, two phalanges each ; 



and the IV. and V., three phalanges each. 



