84 



STEUCTURE AND CLASSIFICATION OF BIRDS 



tensor longus is reinforced by a muscular slip ending in a 

 tendon which is derived from the cucullaris muscle. Another 

 muscle which is also related to the patagialis in an analogous 

 way has been termed the ' biceps slip ' (q.v.) 



Anconceus Longus. This muscle arises from the neck of 

 the scapula alone, by a head which is entirely tendinous or 

 partly muscular, or in addition from the edge of the scapula, a 

 little further away from its junction with the coracoid, by a 

 tendinous head. It is inserted bv a broad tendon on to the 



7 ' P.L 



FIG. 49. TENSOKES PATAGII OF Phcswicoptenis. 



T.I'.L, tens', ir patagii longus ; T.l'.B, tensor patagii brevis : Bi, biceps 

 .-lip: E. ('. A', extensor carpi radialis. (Alter VELDON ) 



elbow joint. Sometimes there is an accessory head from 

 the humerus, which in this case arises, as a rule, in common 

 with the tendon of insertion of the posterior latissimus 

 dorsi. In Palamedea this head is double, the two halves 

 being united by cross tendinous threads. On the whole the 

 humeral head is characteristic of GAREOD'S Homalogonata* 

 and not of the Anomalogonatae ; but there are exceptions on 

 both sides. The breadth of the humeral head varies greatly ; 

 it is sometimes reduced to a thin thread. 



