15. LARUS. 193 



quills broadly edgod with white on tho inner webs; tail-feathons 

 white, except the two or throe central pairs, which are tinged with 

 palest grey : bill deej) red, with a dark siibtorniinal band ; tarsi 

 and toes dark livid red (drying blackish). Total length 13-5 to 14 

 inches, culmcn I'd, wing 11-25, tail 4"6, tarsus I'O, middle toe 

 with claw 1-5. 



The sexes appear to bo alike externally. 



In less mature birds there is a narrow black bar above the 

 terminal white of the 1st quill, thus dividing the white into a tip 

 and a ' mirror.' 



Adult ill ivinter. Like the above, except that the head is white, 

 spotted and mottled with blackish on the upper surface. 



Immature. Similar, but there is a larger proportion of black iu 

 the five outer primaries, the shafts of which are blackish to grey, 

 and the 6th quill has more or less of a black subterminal bar ; 

 shafts of tho middle pairs of tail-feathers hair-lined with black : 

 bill, tarsi, and toos reddish black. 



Young (August). Forehead dull white ; crown and nape greyish 

 brown, darkest below and behind the eye, which retains its white 

 patches ; neck ash-colour ; feathers of the mantle grey above and 

 ash-brown centrally or subtorminally, with pale drab tips ; the five 

 outer quills chiefly black, with small white tips which increase in 

 size ascendingly ; in the (Jlh quiU the outer web is chiefly grey, 

 barred with black, and iu the succeeding quills the dark colour is 

 restricted to the inuer webs ; tail-feathers grey, subtorminally 

 banded with black and tipped with huffish grey, except the outer- 

 most pair ; underparts white : bill and tarsi brown. By the 

 following November the middle of the mantle has become bluish 

 grey, the sooty colour of the primaries is perceptibly paler on the 

 margins of the inner webs, and the blackish bar has considerably 

 diminished in size on the 2nd of the rectrices from the outside. 



Eah. Interior of North America, from the western shores of 

 Hudson Bay and Manitoba inwards, up to Great Bear Lake (breed- 

 ing) ; southwards on migration, along — and west of — the Mississippi 

 Valley, to Corpus Christi, Texas ; through Mexico, and down the 

 Pacific coast, as far as Chile. Once at St. Bartholomew I., West 

 Indies {fide Sundevall). Breeds in marshes. 



a. Ad. sk. Hayes River, west side of II. Saunders Coll. 



Hudson Bay. 

 h, c. Imni. sk. North-West America. Capt. Kellett & Lt. 



Wood, R.N. [P.]. 

 (I. Juv. sk. 49th Parallel, N.W. Amer., North American 



Sept. 1874. Boundary Commis- 



sion [P.]. 

 *■>/• d vix ad. Aransas Bay, S.Texas, June (i^. Salvin-Godman Coll. 



a. Armstrong^. 

 g-m. S 2 !id. ; Corpus Christi, Texas, April Salvin-Godman Coll. 

 n, o. cJ juv. sk. .SO and Sept. 30, Oct. 7 

 (F. B. A.) 

 p. Ad. sk. Progreso, Yucatan, autumn Salvin-Godman Coll. 



(F. Nicholson). 



VOL. XXV. 



