474 STRUCTURE AND CLASSIFICATION OF BIRDS 



Milvago cli inut ngo Melierax polijzon us 



Gypactus barbatns Pohjborus brasiliensis 



DryotriorcJiis xpcctabilis Polyboroides typicus 



Aquila impcrialis Haliaetus albicilht 



Loplwae tics occipitalis Milvus ictinus 



Melierax monograminicus Astur approximans 



a wristward branch (as shown in fig. 226) is given off, the 

 tendon, in fact, bifurcating. FUBBRINGER, however, while 

 figuring the two types, distinguishes in the apparently single 

 tendon of Tinnunculus two separate tendons in close contact 

 for their entire length. 



A further complication is seen in Gijpaetus and Gypo- 

 hierax, 1 where a small recurrent tendon (patagial fan) joins 

 the anterior branch of the bre.vis with the long us, a state of 

 affairs found to characterise Serpentarius, as will be pointed 

 out later. 



The expansor secundariorum - is present in Milvago chi- 

 mango, Harpijhaliaetus coronatus, Falco, Pohjborus, Tinnun- 

 culus, and Microhierax coerulescens ; in others it is absent. 



The anconccus arises in Polyboroides and in some other 

 types by a single head from the scapula, which is partly 

 fleshy and partly tendinous. In Vultur aurieularis, on the 

 other hand, the muscle arises by two completely tendinous 

 heads, so that the muscle has not that value in the classi- 

 fication of the Accipitres that I at one time thought. 3 In all 



1 In GiTiinaiii'titx melanoleucus, which has, as have all the last-mentioned 

 genera, a bifurcate tendon of the brcvis, a small muscular belly ending in a 

 tendon which becomes lost upon the patagium arose on the right side, in a 

 specimen which I dissected, from the extensor muscle near to the end of the 

 anterior branch of the brevis tendon. I am uncertain of the exact homology of 

 this structure in Geranoaetns. 



- For muscular anatomy, &c., of Accipitres see GIEBEL, ' Bemerkungen iiber 

 Cathartcs aura,' etc., Zeitschr. /. d. fjcs. Natww. ix. (1857), p. 420 ; ' Zur 

 Anatomie von Yultiir fulvus? ibid. xxi. (1863), p. 131; 'Zur Anatomie des 

 Lammergeiers,' ibid, xxviii. (1866), p. 149 ; S. HAUGHTON, ' On the Comparative 

 Myology of certain Birds,' P. R. Irish Ac. ix. (1867), p. 524 (crane and goose 

 as well as hawks). He deals with weight only. E. NEAXDEK, Undersukningar 

 af Muxlt-iihititrcn hos sliigtet Buteo, Lund, 1875 ; MILNE-EDWABDS in Rccliercfas 

 Anatomiques, d-c., des Oiscaux Fossilcs dc la France, Paris, 1867. 



'' ' On certain Points in the Anatomy of the Accipitres,' I'. Z. S. 1889,. 

 p. 81. 



