HYPOTHETICAL LIST.’ 
Famity ALCIDZA. 
Cépphus motzfeldi (BENICKEN). Black-winged Guillemot. [2.] 
Uria motzfeldi BENIcKEN, Isis, XV, 1824, 889. (Greenland Seas.) 
North American, but its specific validity not satisfactorily estab- 
lished. (Cf. SresnecEr, Proc. U. S. Nat. Mus., VII, 1884, 210; 
Water Birds N. A., II, 1884, 497, 498). 
Famity LARIDZ. 
Genus CREAGRUS Bonaparte. 
Creagrus BONAPARTE, Naumannia, 1854, 213. Type, by orig. desig., 
Larus furcatus NEBOUX. 
Cre4grus furcétus (NEBoUX). Swallow-tailed Gull. [4.] 
Larus furcatus Nesoux, Zool. Voy. Venus, Atlas, 1842, pl. 10. (‘“‘Mon- 
terey,”’ California.) 
In all probability erroneously accredited to North America. 
1 Consisting of species which have been recorded as North American, but whose status 
as North American birds is doubtful, either from lack of positive evidence of their occur- 
rence within the prescribed limits of the present Check-List, or from absence of satis- 
factory proof of their validity as species. 
