308 PROCEEDINGS OF THE ACADEMY OF 



bird is n Larus. I by no means insist upon its reference to L. brachyrhynchus, 

 Rich, although I have placed it as a synonym of that species, with a query, 

 in consequence of my inability to discover any material discrepancies. The 

 question appears really to hinge upon the identity or non-identity of Larus 

 hrachyrhynchus with the Siberian type of L. canus, which is given by Midden- 

 dorff as a variety {major) of canus, in view of its larger bill and some other 

 peculiarities. I have little doubt of the propriety of referring L. niveus to 

 this Siberian Mew-Gull. 



But, while I thus exclude Larus niveus of Pallas from the Rissa, the Rissa 

 nivea of Bruch and other authors is to be examined. Bruch says of his R. 

 nivea of 1855, that it has the hind toe better developed ; and it is of another 

 species that he says "feet coral-red." While, therefore, he is in error in 

 adducing R. brachyrhyncha, Gould, as a synonym, his species is to be referred 

 (from its description) to the preceding species, R. Kotztbui. 



I quote Ri'ssa nivea, Gr. and Rissa brevirostris, Brandt, as synonyms of the 

 species, on the authority of Bonaparte. 



In the General Report on Birds, Mr. Lawrence gives, under the head of Rissa 

 brevirostris, Brandt, a description taken from Bruch, which applies to the pre- 

 ceding species in most particulars, but the expression, "feet coral-red," is 

 only applicable to the present. Again, under head of Rissa nivea, Bruch, 

 which has been shown above to be the Kotzebui, he copies Gould's description 

 of R. brachyrhyncha. In other words, in his first species he has the synonymy 

 of the present and mostly the description of the preceding species ; and his 

 second, the description of the present species and mostly the synonymy of the 

 preceding. Rissa septentrional is of Lawrence has been already adverted to. 



I am entirely ignorant of the characters and relationships of Larus citriros- 

 tris, Schimper. By Bonaparte it is placed as a synonym of Rissa brachyrhyncha ; 

 this author, perhaps, having overlooked the fact that he had already assigned 

 it, a few pages previously, to L. niveus, Pallas. Judging, however, from 

 Bruclrs description and plate, it must be quite distinct from the present spe- 

 cies, as the bills differ widely in shape. . Bruch says that Bonaparte's L. lamt- 

 schatchensis is an "undoubted synonym" of Larus citrirostris. Bonaparte 

 himself places L. lanntschatchensis as a partial synonym of L. niveus, Pall. It 

 is not impossible, after all, that L. niveus should be distinct from the Mew- 

 Gulls (Larus canus major, Midd. and L. brachyrhynchus, Rich.) both of Siberia 

 and America, and yet be no Rissa, but form a good species, with Larus Icamt- 

 schatchensis, Bp. and L. citrirostris, Schimper, as synonyms. This is the 

 opinion maintained by Bonaparte. 



In the preceding remarks I have endeavored to state the opinions of various 

 writers and my own, as fairly as possible ; considering that in this manner 

 truth is most likely to be attained. I do not profess to have settled so knotty 

 a point satisfactorily, even to myself; and, accordingly, am prepared to adopt 

 any modificatioNS of the views here expressed which future investigations may 

 require. 



Genus IV. Paoopoila Kaup. 



Gavia, Boie, 1822; (nee Moehr. 1752.) 

 Pagophila, Kaup, 1829, (typus Larus eburneus.) 

 Cetosparactes, Macgill. 1842, (typus idem.) 



16. Pagophila eburnea Kaup ex Gmel. 



Larus eburneus, Gmel. 1788. Gavia eburnea, Boie, 1822. Pagophila ebur- 

 nea, Kaup, 1829; Lawr. 1858. Cetosparactes eburnea, Macgill. 1842. 

 Larus candidus, Fabricius, 1780. Larus niveus, Mart, fide Bp. ; (nee 

 Pall. 1811.) 



Sp. char. Culmen straight to the nostrils, then regularly convex ; commis- 

 sure gently curved to the tip, where it is greatly decurved ; gonys straight to 



[June, 



