LAEUS GLAUCUS, GLAUCOUS GULL. 621 



18.50 ; till along culmen, 2.75 to 3.00 ; along rictus, 3.75 ; depth opposite nostrils, 0.80 ; 

 at angle, 0.85 ; tarsus, 3.00 ; middle toe and claw, 2.75. 



One of the largt-st and most powerful of the subfamily, nearly equaliug in these 

 respects the L. mai-inui. The combination of the large size and the extremely light 

 colors render it perfectly easy to distinguish it at a glance. The well-defined, rounded, 

 white apical spots of the primaries of glaucescens at once separate that species. The 

 differences of leucopterus, as shown by the dimensions, may be seen by comparing the 

 measurements given. 



All authors are agreed as to the great variation in size which this species presents. 

 Sabine found one to measure 32 by 65 inches, with a tarsus 3.50 and a bill upward of 

 4 mches long. The dimensions given are, it is believed, about the average. 



Note. — "Larus hutcMnsii/' — In earlier papers I recognized this as a species distinct 

 from L. glaucus, basing characters as follows : 



AduU{Wl)— Entire plumage pure white; shafts of primaries straw-yellow. Bill 

 flesh-colored, blackish on the terminal third. Feet flesh-colored. 



Young. — Head, neck, and upper parts white, mottled with light reddish-brown, ap- 

 pearing on the back as irregular patches, and on the rump as more or less regular 

 transverse bars. Under parts nearly uniform, very pale reddish-brown ; the under tail 

 coverts barred with white. Wings and tail pure white, with yellow shafts. 



Bimendms. — Length, 27.50; extent, 60.00; wing, 17.75; bill along culmen, 2.40 ; along 

 gape, 3.20 ; height at nostrils, 0.70 ; tarsus, 3.40 ; middle toe and claw, 3.50. 



The particular coloration of the bill, however, is against the supposition that the 

 bird is adult, as this coloration is the ordinary style in young birds of this group. I 

 am now disinclined to allow that the bird is anything more than some stage of i. glau- 

 cus, although it is difficult to account for the absence of any shade of pearly-blue on the 

 mantle. In the foregoing synonymy I assign it to glaucus, with this explanation ; and 

 in further elucidation of the question I present the following remarks, just as I find 

 them in my Mss. prepared in 1863 : 



"•Under the above name, and by the foregoing description, I wish to indicate a form 

 of Gull as large, or almost as large, as glaucus, differing from this species mainly iu 

 being pure white all over, and in having a differently colored bill. It looks, indeed, 

 like an albino glaucus ; but, as other species of Gulls are equally liable to albinism, we 

 should not find so many albinos oi glaucus to so few, if any, of other species. Glaucus, 

 as is well known, grows lighter with age, but is never wholly pure white ; at least I 

 have seen none such, nor have I found descriptions of such a condition. And, more- 

 over, the bill of an old glaucus is never of the color of what I call Imtchiiisii. In this 

 respect the bird is like young glaucus, leucopierus, &c. This fact excites suspicion that 

 the bird may be an immature, if not an abnormal, glaucus ; yet I have no more au- 

 thority for saying so than for denying that it is so. I do not know that I clearly recog- 

 nize, or could separate, specimens of young hutchinsil (supposing it to be distinct) from 

 young glaucus, but the adults are not to, be mistaken for each o.ther. 



" I revived this overlooked species in the ' Proceedings,' as above. We have now 

 several specimens in the Smithsonian, from widely separated localities. One of them 

 was taken in winter in New York State. Other specimens are iu Captain Eodgers' 

 collections, from the North Pacific, where the bird is represented to be common. These 

 are noticed by Mr. Cassin, as above quoted. There is a New England specimen in the 

 Museum of the Peabody Academy, at Salem, Massachusetts, mentioned by me, as 

 above, in the Essex Institute Proceedings. In selecting a name for this bird I have 

 been perplexed, rather from not knowing which one to choose than from any dearth of 

 names. Ornithologists differ as to the synonymy. Bonaparte (Oonsp. Av.) calls it 

 ' arcticus, Macgill.' and puts ' argentatus, Sabine,' as a synonym. Both of these au- 

 thors speak of their subjects as having a notable amount of blue on the back — the 

 latter writer especially dwelling on this character ('back pure pearl-gray, with a good 

 .deal of blue,' &c.) Their descriptions, beyond question, refer to leucopterus, as, indeed, 

 one of them (Macgillivray) subsequently affirmed. Sabine gives (Mem. B. Greenland, 

 Trans. Linn. Soc. xii, 1818), under head of L. glaucus, a full and accurate description 

 of hutchinsii, which he considers as a variety of glaucus, ' caused by sickness or a 

 scarcity of supply of food. I have not been able to examine the original notice of L. 

 glacialis, Benicken ;' but Bruch, who adopts that name, speaks of the gull-blue of the 

 upper parts. The name is therefore not to be used in this connection. Bonaparte 

 gives as a synonym ' leuconotus, Auct.', though what authors he refers to I have not 

 been able to determine. This name would seem to belong here. I do not know 

 whether or not it antedates hutcMnsii, proposed in 1831, for a bird that can be no other 

 than the one now under discussion. Bonaparte's Conspectus Gaviarum differs much 

 from his Conspectus Avium with regard to this species. In the latter he admits it as 

 valid, assigning specific characters and synonymy. In the former he discards it, and 

 scatters the synonymy indiscriminately among several species." 



