DUBLIN NlTUIUL HI8T0BT SOCIETT. 85 



ing:— Bill dusky orango at the base, dark at the tip, form sleuder, 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 ; back, 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, mar- 

 gined with black on both webs ; third, white increases on the outer margin, 

 more black bordering the inner margin, and the extremity of the feather const- 

 derably 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 choco- 

 late brown, edged with dull white ; underneath, tail white, with slight markings 

 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 de- 

 scriptions of L. Bonapartii of Richardson, L. capistratus of the Prince of Mu- 

 signano, L. capistratus of Yarrell, and the L. ridibundus of Montagu, Selby, 

 and others, 1 am inclined to refer the bird before us to one of those varied forma 

 and gradations of the L. ridibundus, as they so nearly correspond with the state 

 of the second change described by Montagu and Latham, that 1 cannot separate 

 the one from the other. Mr. Thompson has very judiciously decided L. capis- 

 tratus of Yarrell to be but a variety of L. ridibundus, and the examination of 

 numerous specimens of both have shown such differences in their relative pro- 

 portions ana size, that it would seem that much dependence could not be placed 

 on measurements. Mr. Thompson, at p. 339, alludes to an adult bird of L. ridi- 

 bundus having been shot at Lough Clay, smaller in proportions than any forma 

 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 

 smaller size — hence we may naturally infer, that those incubations may affect 

 the growth of the birds. Now, the different gradations of L. ridibundus, so care- 

 fully and accurately noticed by Montagu, I will concisely submit. In the first 

 plumage of the young of L. ridibundus, it is nearest to tne description of Ray's 

 brown Tern ; the second material chanee brings it to the Lathamian brown g^l, 

 of the second supplement of the general synopsis of Latham, and which exactly 

 accords with the description by Slontagu 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 as L. ridibun- 

 dus. In several of the characters detailed by Mr. Thompson, particularly of 

 the Tern-like form and length of the wings, L. Bonapartii is so nearly identical 

 with forms described both of L. capistratus 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, from 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 sub-emarginate ; summer plumage, head only with a brown hood ; winter, 

 no hood. Brown-masked gull (Larus capistratus) — Nob. Am. Orn. IV. PI. In- 

 habits the north of both countries; not very rare during autumn on the Dela- 

 ware, 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 size, and its still more slender torn-like 

 bill. These references are shown to prove the confusion that might possibly arise 

 in the distinenishing allied species of birds in the immature plumage, more es- 

 pecially the Larida;, or the gulls ; and, as Wilson most truly remarks, on the 

 much- varied species L. ridibundus, "that less confusion would arise among au- 

 thors if they would occasionally abandon their accustomed walks, their studies, 

 and their museums, and seek correct knowledge in the only place where it is to 

 be obtained— in the Great Temple of Nature." 



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