1919-] ^^'^' Birds of the Anylo-Egyptian Sudan. 635 



Lybius bidentatus sequatorialis. 



Melanobucco cequatorialis Shelley, Ibis, 1889, p. 476: 

 Hparo. 



Lybius tequutoria/is (Sliell.); Reicliw. V. A. ii. p. 111). 



[Chr. coll.] 4 Meridi Jan., 2 Mt. Bagiuzi Mch., 

 2 Yambio Mch. E.G. 



This subspecies takes the place of the West African 

 L. b. bidentatus from the Shari river eastwards to Mau and 

 southern Abyssinia, but it does not seem to have been met 

 with by Butler though mentioned by Heuglin as rare on the 

 upper Nile. 



Neumann (Bull. B. O. C. xxiii. 1908, p. 29) separates the 

 southern Ethiopian form as L. b. cethiops on account of its 

 slightly smaller size, but there appears to be a good deal of 

 variation in this respect, and there is hardly any ground for 

 recognizing it as distinct. The wings of the Christy birds 

 vary from 95 to 105 mm. 



Lybius leucocephalus. 



Laimodon leucocephalus De Filippi, Rev. Mag. Zool. 1853, 

 p. 291 : White Nile. 



Lybius leucocephalus (Fil.) ; Reichw. V. A. ii. p. 121 ; 

 Butler, Ibis, 1908, p. 246, 1909, p. 87. 



[B. coll.] 1 Menyah Jan., 2 Gardain Jan., 1 Ayem 

 Jan., 2 Doleiba May, E.G. ; 1 Kajo Kaji Mch. L.E. 



[Chr. coll.] 1 Mt. Baginzi Mch., 3 Wau July-Aug. 

 E.G. ; 3 Yei Nov. Dec. L.E. 



Claude Grant suggests in ' The Ibis,' 1915, p. 438, that 

 this bird may be the young of L. senex. This we cannot 

 agree with, as no specimens of L. senex are known from the 

 main range of _L. leucocephalus. No doubt they are closely 

 related and were developed from a common stock, but we 

 cannot admit their identity or even that they are subspecies 

 of the same bird at the present time. One of the birds 

 collected by Christy at Wau has considerabW more white on 

 the belly than the others, thus showing a tendency to 

 L. sene,v, which is possibly the ancestral form. 



