790 Messrs. Sclater and Mackwortli-Praed on [Ibis, 



Mespphoyx inter medi us brachyrhynchus. 



Herudias [Eyretta'] hrachyrliynchos Brehni, J. f. O. 1858, 

 p. 471 : Blue Nile. 



Herudias brachijrhyncha Reichw. V. A. i. p. 389; Butler, 

 Ibis, 1905, p. 372, 1908, p. 255. 



Recorded by Heugliu from Kordofan and the White and 

 Blue Niles. There are specimens in the Museum from the 

 Sobat River. 



Demigretta schistacea. 



Ardea{Lepterodias)schistacea Hempr. & Ehr. Symb.Phys., 

 Zool. ii. 1828, fol. i. pi. 6: Northern Red Sea. 



Herudias schistacea Reicliw. V. A. i. p. 387. 



[C. & L. coll.] 2 Port Sudan Dec. & Apl. R.S. 



One of these birds is in grey plumage changing to white, 

 the other in almost complete white dress. This bird has a 

 long tarsus, and is apparently quite distinct from D. gularis 

 from the rest of Africa, which also does not appear ever to 

 have a white phase. Nor do these birds seem to us to be 

 the same as the Indian form [Ardea asha Sykes, P. Z. S. 

 1832, p. 157: Deccan), in which the grey phase is con- 

 siderably paler. We do not think, however, that there are 

 sufficient grounds to justify its separation from the genus 

 Demigretta. We cannot say from present material whether 

 this species has two dimorphic forms — a grey and a white — 

 or whether one is the young of the other. Hemprich and 

 Ehrenberg concluded that the white form was the young 

 one, and this may prove to be the case ; but what we have 

 little doubt of is that, unlike the Australian Reef-Herons 

 (cf. Mathews, Birds of Australia, iii. p. 454), these are both 

 forms of the same species. We can trace no record of the 

 true 1). gularis [Ardeu gularis Bosc, Actes de la Soc. 

 d^Hist. Nat. Paris, i. 1792, p. 4, pi. 2: Senegal River) ever 

 having occurred in the Sudan, the specimen labelled ''Nile'' 

 (Sir F. Galton) mentioned iu the British Museum Catalogue 

 being an undoubted example of D. schistacea, and the older 

 authors not having separated the two birds. This species 

 appears to be an almost exclusively marine form, while 

 D. gularis is also an inland form. 



