96 PROCEEDINGS OF SOCIETIES. 



the Bonapartian gull (Larus Bonapartii), and most kindly, by Mrs. Baker, has 

 been sent to be recorded in the proceedings of this Society. This small gull was shot 

 at Skerries, on the 18th of February last, by Captain Watkins, of the Northampton 

 Regiment of Militia. Not having examined the bird in its recent state, I had no 

 opportunity of learning accurately its measurement or weight. Mr. Robert J. 

 Montgomery, who first drew attention to the characters, was so satisfied of their 

 identity with those recorded by Thompson, that he, on very good grounds, assumed 

 the present specimen to be the Bonapartian gull described by that author. The 

 bird is immature ; and as I do not place much reliance on measurements in the 

 young state, I have drawn out the following : Bill, dusky orange at the base, 

 dark at the tip, form slender, similar to L. ridibundus ; a black spot at the anterior 

 corner of each eye ; a dark mark behind each ear ; crown of the head, slightly 

 marked ; forehead and all under parts, white ; black scapulars, greater coverts of 

 the secondaries, and the upper series of the smaller coverts, light pearl gray ; several 

 rows of brown spots on the small wing coverts, edged with dull white ; two first 

 primaries, white, margined with black on both webs ; third, white increases on the 

 outer margin, more black bordering the inner margin, and the extremity of the 

 feather considerably more tipped with black ; fourth, very nearly all white in the 

 margin, dark margin of the inner fainter ; feather, pale gray ; tail, with a band of 

 chocolate brown, edged with dull white ; underneath tail, white, with slight mark- 

 ings of pale chocolate brown at the extremity ; ridges of the wings, white, with a 

 slight dark mark. In the recent state, Mrs. Baker informs me, that the legs were 

 of a pale flesh colour. 



Now, on comparing these characters with the descriptions of L. Bonapartii of 

 Richardson, L. capistratus of the Prince of Musignano, L. capistratus of Yarrell, 

 and the L. ridibundus of Montagu, Selby, and others, I am inclined to refer the 

 bird before us to one of those varied forms and gradations of the L. ridibundus, 

 as they so nearly correspond with the state of the second change described by 

 Montagu and Latham, that I cannot separate the one from the other. Mr. Thomp- 

 son has, very judiciously, decided L. capistratus of Yarrell to be but a variety of 

 L. ridibundus, and that the examination of numerous specimens of both have 

 shown such difference in their relative proportions and size, that it would seem that 

 much dependence could not be placed on measurements. Mr. Thompson (at 

 p. 339, vol. iii., "Birds of Ireland") alludes to an adult bird of L. ridibundus hav- 

 ing been shot at Lough Clay, smaller in proportions than any forms described of 

 either L. ridibundus or L. capistratus. We are aware how the eggs of gulls vary 

 in size, even in the same nest, and that when the first, or early eggs of the season, 

 are taken, the eggs of the succeeding layings are, in general, of a smaller size 

 hence we may naturally inter that those incubations may affect the growth of the 

 birds. Now, the different gradations of L. ridibundus, so carefully and accurately 

 noticed by Montagu, I will concisely submit. In the first plumage of the young of 

 L. ridibundus, it is nearest to the description of Ray's brown Tern ; the second 

 material change brings it to the Lathamian brown gull, of the second supplement 

 of the general synopsis of Latham, and which exactly accords with the description 

 by Montagu of a recent specimen shot on the 14th of February, and agrees in 

 most characters with the specimen before you. The next change brings it to the 

 brown -headed gull of Latham, L. erythropus, and approaching to L. capistratus, 

 and the fourth change perfects it to L. ridibundus. In several of the characters, 

 detailed by Mr. Thompson, of L. Bonapartii, particularly of the Tern-like form 

 and length of the wings, so many are identical with forms described both of L. ca- 

 pistratus and L. ridibundus, that it is difficult to separate them. 



I will here give the characters of Larus capistratus of Temm., by the Prince of 

 Musignano, in his synopsis of the birds of the United States (No. 293) Mantle, 

 pearl-gray ; quills, black at the point, outer white, internally pale-ash ; shafts, white; 

 bill, very slender ; tarsus, less than one inch and a half; tail, subemarginate; summer 

 plumage, head only with a brown hood ; winter, no hood. Brown-masked gull 

 (Larus capistratus) Nob. am. Orn. IV. pi. inhabits the north of both countries ; 

 not very rare during the autumn on the Delaware, and especially the Chesapeake ; 

 found as far inland as Trenton ; very rare on the coasts of Europe ; closely allied 

 and similar to L. ridibundus of Europe, hardly distinguished but by its smaller 



