484 STRUCTURE AND CLASSIFICATION OF BIRDS 



the nasal septum in the middle line. In Gyparohus papa, at 

 any rate, there is a small medio-palatine. The lacrymal (at 

 least in Cathartes atratus) is a smallish bone completely 

 fining a notch in the frontal margin ; its descending process 

 ankyloses with the ectethmoid, forming the usual ring. In 

 Gyparchus papa the orbital portion of the lacrymal is greatly 

 reduced ; the nostrils are not so elongated as in Cathartes ; 

 the palatal bridge is more plainly an alinasal fold. The 

 bony nostrils are holorhinal, but much more elongated than 

 in the Falconidae ; there is no trace of an ossified internarial 

 septum. 



Of fossil Accipitres the remains of a number of different species 

 have been found. The most interesting of these, on account of its 

 age, is the Lithornis vultwinus of Owen,' from the London clay. 

 It had been held to come nearest to Cathartes, an interesting fact 

 in view of its occurrence in this country ; but Lydbkkbe regards 

 it as clearly accipitrine and allied to Accipiter and Circus. Har- 

 pagornis,^ from the Pleistocene of New Zealand, was a large bird, 

 one and a half time the bulk of a golden eagle, also belonging to 

 the same division of Accipitres. Teracus and PalcBohierax are 

 extinct genera from the lower Miocene of Prance, known only by 

 femur and tarso-metatarsus respectively. They are also probably 

 true falcons. Serpenta/rius is known by an extinct form, S. rohusius, 

 from the lower Miocene of the same country. 



The following table shows the main differences between 

 the several families of the Accipitres : — 



' ' Description of the Fossil Eemains of ... a Bird (Lithornis vultti/nnus) 

 from the London Clay,' Trans. Geol. Soo. (2), vi. 1841, p. 206. 



" Of. Haast in Trans. N. Zealand Inst. iv. 1871, p. 192, and ibid. vi. 1874, 

 p. 64, and Owen in Extinct Birds of New Zealand. 



