Birds from the White Nile. 465 



[I only saw one Lesser Black-backed Gull, near Ecl-Duem. 

 — R. M. H.] 



198. LiMNOCORAX NIGER. 



Limnocorax niger (Gmel.) ; Grant & Reid, p. 694. 



a, b. cJ et cJ imm. Kaka, 7th May. Nos. 441 & 445. 



c, d. ^ imm. Kaka, 18th April. 



Iris crimson ; bill greenish chrome ; upper portion of 

 eyelid coral-red ; legs and feet dusky red, brighter at and 

 above the tibio-tarsal joint. 



[I only saw a few individuals of the Black Rail. Several 

 times I heard it utter its cry in the flags, but could not 

 Hush it. Mr. Loat kindly gave me two skins which he had 

 procured. — R. M. H.] 



199. TURTUR DECIPIENS. 



Turtur decipiens Finsch & Hartl. Vog. Ost-Afr. p. 544 

 (1870); Salvad. Cat. B. Brit. Mus. xxi. p. 420 (1893); 

 N. C. Roths. & Wollast. p. 25. 



Turtur ambiguus Bocage, Orn. Angola, p. 386 (1877) ; 

 Salvad. Cat. B. Brit. Mus. xxi. p. 419 (1893) ; Witherby, 

 p. 266. 



a. S • Fashoda, 30th March. No. 255. 



h. S ' El-Kawa, 20th May. No. 525. 



c-s. S ? . Ed-Duem, 22nd May. Nos. 542, 543, 559. 



Iris yellow ; bill vinaceous ; legs and feet pinkish. 



I think there can be no doubt that 2\ decipiens and 

 T. ambiguus are synonymous. Mr. Witherby and Messrs. 

 Rothschild and "NVollaston have pointed out certain differ- 

 ences in the length of the wing and the width of the white 

 tips to the tail-feathers, but, as will be seen by the following 

 measurements, these characters appear to be sexual, not 

 specific. 



The specimen from Argo Island, Dongola (one of the 

 types of Columba collaris Plempr. & Ehr.), which Count 

 Salvadori in the ' Catalogue of Birds ' refers to C. decipiens, 

 appears to me to be an unusually rufous specimen of the 

 bird that he calls T. ambiguus. It is in worn plumage, and 



