820 Messrs. Sclater and Mackworth-t*raed on [ibis 



Larus (Adelarus) hemprichi. 



Adelurus hemprichii Brucli, J. f. O. 1853, j). lOO: Red 

 Sea. 



Larus hemprichi lleichw. V. A. i. p. 49. 



[C. & L. coll.] 1 Port Sudan Dec. R.S. 



Rhynchops flavirostris. 



Rhynchops flavirostris Vieill. Nouv. Diet. iii. 1816, 

 p. 383 : Senegal [op. cit. xxix. p. 283) ; lleichw. V. A. i. 

 p. 7Q; Butler, Ibis, 1905, p. 382. 



[13. coll.] 4 Khartoum Apl. Nov. Dec. ; 2 (pull.) near 

 Roseires, Sen. 



The Skimmer is found on all the larger rivers. 



Hydrochelidon leucoptera leucoptera. 



Sterna leucoptera Terara. Man. d'Orn. 1815, p. 483: 

 Mediterranean. 



Hydrochelidon leucoptera Reichw. V. A. i. p. 71 ; Butler, 

 Ibis, 1905, p. 382. 



[B. coll.] 3 Khartoum Apl. 20 and " autumn " ; 

 8 Fashoda (Kodok) May, U.N. 



Hydrochelidon nigra nigra. 



Sterna nigra Linn. Syst. Nat. 10th ed. 1758, p. 137: 

 Europe, restricted type-locality Sweden. 



Hydrochelidon nigra Reichw. V. A. i. p. 70 : Butler, Ibis, 

 1905, p. 382. 



Hydrochelidon leucopareia leucopareia. 



Sterna leucopareia Temu). Man. d'Orn. 2nd ed. ii. 1820, 

 p. 746 : Hungary. 



Hydrochelidon hybrida (Pall.) Reichw. V. A. i. p. 72 : 

 Butler, Ibis, 1905, p. 382. 



[B. coll.] 3 Kliartoum Apl. 23-26. 



All three species of Hydrochelidon are regular winter 

 migrants to the Nile Valley, H. nigra being the least 

 common. 



