1889.] 



ANATOMY OF POLYBOROIDES. 



79 



I find an identical arrangement of these tendons in Circus mavrus, 

 and they appear to be exactly the same (judging from a MS. sketch 

 by Forbes) in Spizaetus occipitalis and Aqiiila impei-ialis. In 

 Milvago chimachima and in Haliaetus albicilla and Astitr ajiprox- 

 imans (Forbes, MS.) the tendon is single, but there is a trace of the 

 second tendon in a short fibrous slip wliich, arising from near the 



Fig. 1. 



Ani: 



Tensores patagii and ether muscles oi Polyhor aides typicus. 



t.p.l, tensor patagii longiis ; f.p.hr, tensor patagii brevis ; Anc, anconeus ; B, 



deltoid. 

 (The dotted parts represent tendons in this and the following figure.) 



insertion on to the forearm of the tensor patagii tendon, ends upon 

 the patagium. This tendinous band may, however, perhaps be 

 considered as the equivalent of the tendon which in other Accipitres 

 (v. infra) unites the tendon of the tensor patagii longtis with that 

 of the tensor patagii brevis at the insertion of the latter on to the 

 forearm. 



In Gypohierax^ the tensor patagii brevis refembles thatofPo/y- 

 boroides except that the outerrr.ost of the two tendons near to the 



^ Fiirbringer, Untersuchiingen z. Morph. und Syst. d. Vogel, pi. xxii. fig. 9. 



