84 



STEUCTURE AND CLASSIFICATION OF BIRDS 



tensor longus is reinforced by a muscular slip ending in a 

 tendon which is derived from the cucuUaris muscle. Another 

 muscle which is also related to the patagialis in an analogous 

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



AnconcBus 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 by a broad tendon oii to the 



Pig. 49. — Tensores Patagii of Phmnicopterus. 



T.P.L, tensor patagii longus ; r.P.B, tensor patagii brevis ; 6i, biceps 

 slip ; E.C.R, extensor carpi raclialis. (After Weldox.) 



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 la'tissimus 

 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 Gaerod's Homalogonatse 

 and not of the Anomalogonatse ; but there are exceptions oh 

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

 it is sometimes reduced to a thin thread. 



