XIV.] CHIROPTERA. 229 



is more normal. In Galeopithccus the coracoid is greatly 

 developed and bifurcated. 



All known members of the order have large clavicles, with 

 the exception of Potamogale^ a rare aquatic form from 

 West Africa. 



In the Chiroptera the scapula is large, of an oval form, 

 and chiefly formed by the postscapular fossa, the anterior 

 fossa being extremely small. The former is divided into 

 two or three sub fossae by ridges. The spine is short and 

 moderately high, with a large and simple acromion. The 

 coracoid is long and curved, often simple (as in Pteropus) 

 sometimes forked (as in Pipistrellus). 



The clavicle is very long and curved. The " mesoscapular 

 segment " on the outer end is soon lost, but the precoracoid 

 ossifies separately. The omosternum is reduced to a 

 cuneiform fibro-cartilage. A rudiment of the sternal end of 

 the coracoid is often present as " a flat, reniform flap of 

 cartilage, feebly ossified by endostosis, wedged in between 

 the clavicle and the first rib " (Parker). 



The RoDENTiA ofter great diversities in the condition of 

 the shoulder girdle. The scapula is generally high and 

 narrow, and the acromion long. Sometimes the acromio- 

 scapular notch is so deep, that the actual spine only occupies 

 a short space near the supra-scapular border, and it is com- 

 pleted by a very long and slender acromion (as in the Coypu, 

 Myopotamus). There is often a long metacromion, as in the 

 Hare ; but in others, as the Beaver, there is no such process. 

 The coracoid is always a small blunt hook. 



In a few forms the clavicle is altogether absent, in some it 

 is well developed, and various intermediate stages between 

 these two extremes are met with. In some species, as the 

 Guinea Pig and Rabbit, although no trace of this bone is 

 found at birth, it becomes developed at a later period. In 



