14 ALLEN'S NATURALIST'S LIBRARY. 



the others in length. The tarsus is short, being less than the 

 middle toe and claw in length, and the tail is very short, being 

 less than one-third of the length of the wing. 



I. THE CASPIAN TERN. HYDROPROGNE CASPIA. 



Sterna caspia, Pall. Nov. Comm. Petrop. xiv. i. p. 582, tab. xxii. 



fig. 2 (1770) ; Dresser, B. Eur. viii. p. 289, pi. 584 (1877) ; 



B. O. U. List Brit. B. p. 182 (1883); Saunders, ed. Yarrell's 



Brit. B. iii. p. 536 (1884); Seebohm, Hist. Brit. B. iii. 



p. 268(1885); Saunders, Man. Brit. B. p. 625 (1889); 



Lilford, Col. Fig. Brit. B. part xxviii. (1894). 

 Sylochelidon caspia, Macgill. Brit. B. v. p. 626 (1852). 

 Hydroprogne caspia, Saunders, Cat. B. Brit. Mus. xxv. p. 32 



(1896). 



Adult Male. General colour above pearly-grey, the rump and 

 upper tail-coverts like the back and hardly any paler in tint ; 

 wing-coverts like the back, the bastard-wing and primary- 

 coverts rather paler grey and more frosted in appearance ; 

 primaries grey with white shafts, the greater part of the webs 

 frosted, the inner web blackish along the inner margin, this 

 blackish shade increasing in extent towards the outermost 

 primaries, and occupying the entire inner web of the first one ; 

 secondaries like the back, with the inner webs slightly more 

 dusky-grey ; tail pearly-grey, with white shafts to the feathers, 

 the outermost pointed and only slightly exceeding the others 

 in length ; crown of head and nape glossy black, the crest not 

 elongated ; this black extending below the eyes in a straight 

 line from the base of the upper mandible across the lores ; 

 remainder of the lores, sides of face, ear-coverts, and a spot 

 under the eyes white, like the entire under surface of the body; 

 axillaries and under wing-crests white, the inner face of the 

 primaries distinctly blackish; "bill vermilion-red, sometimes 

 horn-coloured at tip ; tarsi and toes black " {Saunders). Total 

 length, 19 inches; culmen, 2*65 ; wing, 16*5 ; tail, 5*5 ; tarsus, 

 r8. 



Adult Female. Not to be distinguished from the male in 

 colour, but with a weaker and less brilliantly coloured bill. 

 Total length, 19 inches; culmer 2*5; wing, i6'6; tail, 6*2 ; 

 tarsus, 1*65. 



