84 
ALLEn's naturalist’s LIBRAkV. 
tinguished from those of the Kittiwake by their greater gloss, 
the small excrescences are not so crowded together, and are 
a little more flattened than they usually are in the last- 
mentioned species. Axis, 2T5-2'4 inches ; diam., i'65-i75. 
THE KITTIWAKE GULI..S. GENUS RISSA. 
/iissa, Stephens, in Shaw’s Gen. Zool. xiii. part t, p. 189 (1826). 
Type, i?. iridactyla (Linn.). 
The chief character which distinguishes the Kittiwakes from 
the rest of the Gulls is the rudimentary condition or absence of 
the hind toe. The tarsus is much shorter than the middle toe 
with its claw, and the tail shews a slight tendency to be forked. 
Mr. Howard Saunders admits two species of Kittiwakes, out- 
own familiar species {R. tridactyla) with dark brown feet and 
white under wing-coverts, and R. brevirostris, from the Arctic 
Pacific Ocean, with vermilion-coloured feet and grey under 
wing-coverts. A third form, R. pullicaris, with a slightly more 
developed hind-toe than in normal R. tridactyla, and chiefly — 
but not exclusively— from the North Pacific, is recognised by 
some American naturalists, but is disallowed by Mr. Saunders. 
I. THE KITTIWAKE GULL. RISSA TRIDACTVLA. 
Larus tridadylus, Linn. Syst. Nat. i. p. 224(1766); Seebohm, 
Hist. Brit. B. iii. p. 340 (1885). 
Rissa tridactyla (Linn.), Macgill. Brit. B. v. p. 515 (1S52); 
Dresser, B. Eur._ viii. p. 447, pis. 607, 608 (187S); 
B. O. U. List Brit. B. p. 187 (1883); Saunders, ed. 
Yarrcll’s Brit. B. iii. p. 650 (18S4) ; id. Man. Brit. B. 
p. 667 (1889) ; Lilford, Col. Fig. Brit. B. part xxiv. 
(1893); Saunders, Cat. B. Brit. Mus. xxv. p. 305 (1896). 
Adult Male. — General colour above light slaty-grey, with 
narrow white ends to the scapulars ; wing-coverts grey like the 
back ; bastard- wing, primary-coverts, and quills light slaty-grey, 
the inner primaries fringed at the ends, and the secondaries 
narrowly tipped with white ; the outer primaries gre)', white 
along the inner webs ; first primary black along the outer web, 
and also for two inches at the tips ; the second and third 
primaries also black at the ends, this black tip decreasing on 
