6 ALLEN'S NATURALIST'S LIBRARY. 



has been known to capture dragon-flies on the wing, and, 

 according to Mr. Howard Saunders, it has been seen by Mr. 

 F. S. Mitchell to u swoop down on the field-crickets (Acheta 

 campestris) during their momentary appearance at the entrances 

 of their burrows." 



Nest. The Black Tern does not begin to nest before the 

 end of May, and it then breeds in colonies in the marshes or 

 by shallow pools. The nest is a substantial structure of 

 decaying plants and weeds, on heaps of wrack which rise and 

 fall with the water, or on the firmer hummocks of the bog. 



Eggs. Three in number only. Ground colour varying from 

 deep clay- colour or pale chocolate to greenish-grey and stone- 

 colour or buff, the markings generally consisting of black 

 blotches, which are mostly confluent. Sometimes the markings 

 are smaller and take the form of scattered dots or scribblings. 

 The underlying spots are grey and are not very distinct. In the 

 Seebohm collection in the British Museum there are some 

 specimens in which the spots and blotches are perceptibly 

 rufous, though generally they range from a dark chocolate- 

 brown to absolute black. Axis, i '3-1 '45 inch; diam., 0.9 

 -1-05. 



II. THE WHISKERED TERN. HYDROCHELIDON HYBRIDA. 



Sterna hybrida, Pallas, Zoogr. Rosso- Asiat. ii. p. 338 (1811); 

 Seebohm, Hist. Brit. B. iii. p. 260 (1885). 



Hydrochelidon kucopareia (Natt.) ; Macgill. Brit. B. v. p. 663 

 (1852). 



Hydrochelidon hybrida^ Dresser, B. Eur. viii. p. 315, pis. 588, 

 589 (1887); B. O. U. List Brit. B. p. 184 (1883) ; Saun- 

 ders, ed. Yarrell's Brit. B. iii. p. 527 (1884); id. Man. Brit. 

 B. p. 621 (1889); Lilford, Col. Fig. Brit. B. part, xxviii. 

 (1894) ; Saunders, Cat. B. Brit. Mus. xxv. p 10 (1896). 



Adult Male. General colour above light slaty-grey; lower 

 back, rump, upper tail-coverts and tail of the same colour as 

 the rest of the back, the outermost tail-feather being white 

 along the outer web ; wing-coverts like the back ; quills dusky, 

 frosted with pearly-grey on the outer webs ; the shafts of the 

 primaries white, the outer ones with the greater part of the 



