ACCIPITRES 475 



there appears to be an accessory tendinous origin from the 

 humerus. The pectoralis primus is commonly divisible 

 into two layers, but not in Milvago and Dryotriorchis. 



The deep flexor tendons of the foot belong in the 

 majority of species to type described above on p. 101. But 

 there are a few variations of the typical arrangement. In Astur 

 tibialis the slip to digit II. is present, but it is very small. 

 In Baza, on the other hand, the vinculum is alone present, 

 there being no special shp to the tendon supplying digit II. 



In Dryotriorchis spectabilis, Vultior auricularis, and 

 Milvus ictinus, the fibres of the vinculum are perfectly 

 continuous with the slip to digit II., and form with it one 

 single band of connection. 



Both peroneal muscles appear to be present in the 

 Accipitres. 



All genera have the ambiens and the femorocaudal. In 

 Falco and Circus maurus there is also a slender semi- 

 tendinosus?- GlutcBus I. is generally absent, gluteus V. 

 commonly but not always present. 



The syrinx of the Accipitres is of the ordinary tracheo- 

 brojochial form. ,; 



In Falco peregrinus the intrinsic muscles. are inserted on 

 to a transversely elongate fibrq-cartilaginous bar which runs 

 across the interannular membrane of bronchial semi-rings 

 1 and 2. This membrane is very wide, owing to the fact 

 that the first bronchial semi-ring is much arched, the con- 

 cavity being downwards, while the second semi-ring is equally 

 arched, but the concavity is upwards. None of the tracheal 

 rings are fused, and the last gives rise to a pessulus. F.. 

 candicans, F. lanarius, F. biarmicus, F. Feldeggi, F. cesalon, 

 -F. sacer are perfectly similar, and the bronchidesmus (in those 

 specimens in which it had been preserved) is complete. 



Much like the syrinx of Falco is that of Hieracidea 

 berigora ; 1 can, indeed, detect no differences. So too 

 Titmunculus alaudarius and Frythropus vespertinus. In 



' FoEBES in a MS. note records what I call ' semiteudinosus ' in Microhierax 

 coerulescens as a product of the division of the semimembranoaus on account 

 of its origin from Ischium and pubis. 



