1 5 8 ELEMENTAR Y ANA TOM Y. [LESS. 



toed Sloth, where it joins the acromion. It may be not only 

 long, but also forked, as in the little Pipistrelle Bat. It may 

 also join the clavicle, as in the Three-toed Sloth and Mole. 



As has been said, this part may even in man's class (viz. in 

 Monotremes) be a large distinct bone connecting the scapula 

 with the sternum, and having an additional flat bone placed 

 in front of the inner end of the coracoid, called the epi- 

 coracoid, and a distinct rudiment of the epicoracoid may be 

 found in a higher Mammalian form, e.g. in Sorex. 



The coracoid shares with the scapula the office of forming 

 the glenoid surface for the humerus, and it may become fused 

 with the clavicle, as in the Mole. 



The coracoid may not only be a large bone rivalling or 

 exceeding the scapula, as in Birds, but there may be complex 

 structures divisible in zootomy into coracoid and epicoracoid, 

 as before said, and also in addition a part termed pre-cora- 

 coid, which, though essentially related to the coracoid, will yet 

 be more conveniently spoken of in treating of the clavicle. 



FIG. 133. SHOULDER GIRDLE OF A BIRD (DIVER). (After Parker.) 



c, coracoid (its lower end abuts against the sternurti here removed) ; cl, the 

 clavicles (merrythought) ; sc, the scapula the rounded glenoid surface is 

 indicated in the scapula just where it joins the coracoid. 



These coracoid elements may take the form of a large car- 

 tilaginous sheet passing down from the glenoid surface to the 

 middle line of the breast, as in Efts ; or may appear as two 

 bones so passing down on each side, one in front of the 

 other, as in the Frogs ; or as a large sheet of bone and carti- 

 lage often more or less perforated, as in many Lizards. 



Instead of a single glenoid surface (as we find in all Ver- 

 tebrates above Fishes which have pectoral limbs), we find 

 what may possibly be several distinct glenoid surfaces, as 

 e.g. three in Raia clavata. 



Where the coracoids are in the form of large lamellae, they 

 may overlap one the other, as in Batrachians, e.g. Salaman- 

 dra and the Frog. 



The coracoid and scapula may form one cartilaginous 

 whole, while the supra-scapula remains distinct, as in Raia 





