Arrangement of the Gulls. 489 



constitute no more than its specific character, and it would 

 form even a very bad specific distinction when it is common 

 to two such distinct gulls as the kittiwake and the sabine. 

 So, leaving it out as a generic character, let us see how the 

 two groups stand. Mr. Eyton declares that the birds of his 

 new sub -genus have dark heads in their summer plumage ;— 

 on turning to the account of the Sabine Gull in the Linnean 

 Transactions, we find "Capite nigricante, torque cervicale 

 nigro," therefore the two sub-genera agree in what Mr. Eyton 

 pronounces to be the most important character of his sub-ge- 

 nus Chroicocephalus; as they agree in the most important, 

 we shall also find them agreeing in the most neglected cha- 

 racters, ; — for instance, " tarsi slender" and " thighs consider- 

 ably denuded" may be given as generic characters with equal 

 truth to both, Sabine's Gull possessing both characters to a 

 very eminent degree. The character, "hind toe perfect," be- 

 longs also equally to both, so that as the two groups agree 

 perfectly in their habits, as far as these are known, are per- 

 fectly alike in their organization, and when Xema possesses 

 in a very eminent degree the characters which have been 

 deemed most important in the sub-genus Chroicocephalus, 

 and as they agree in all the minor characters, with the ex- 

 ception of the form of the tail, (which I have shewn, by refe- 

 rence to the sub-genus Rissa, to be wholly unfit to be em- 

 ployed as a generic character), I am sure my readers will join 

 with me as to the propriety of uniting the two groups We 

 have now but to do with the two sub -genera Larus and Chroi- 

 cocephalus. On comparing the characters of these two groups 

 we shall find that they agree in almost every particular. 

 "Hind toe perfect" is given as the first character of both 

 groups ; the second character in Larus is "tarsi strong," and 

 in Chroicocephalus, "tarsi slender," but here two such vague 

 terms are employed, that we could not attach any exact mean- 

 ing to them, they appearing to leave it as quite a matter to 

 be decided by each individual's acceptation of the terms, and 

 I am quite satisfied that there is no universal difference in the 

 strength of the tarsi in the two groups. The third character 

 of Larus is " thighs feathered nearly to the joints." In Chroi- 

 cocephalus it is "thighs much denuded," which means pre- 

 cisely the same thing ; for, I think you will find that any gull 

 having his thighs much denuded, will be perfectly described 

 by the words "tarsi feathered nearly to the joints ;" the cha- 

 racters of the tail are the same in both, and now the only re- 

 maining character is "head white in the winter and summer 

 plumage" in Larus, and "head dark coloured in the summer 

 plumage" in Chroicocephalus. But when we consider that, 



