6 
ALLKN'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 “ swoop down on the field-crickets (Acheta 
campesiris) 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 blotclies are percejitibly 
rufous, though generally they range from a dark chocolate- 
brown to absolute black. Axis, 1-3-1 -45 inch; diam., 0.9 
-1-05. 
II. THE WHISKERED TERN. HYDROCHELIDON HYBRIDA. 
Sterna hyhrida, Pallas, Zoogr. Rosso-Asiat. ii. p. 338 (i8it) ; 
Seebohm, Hist. Brit. B. iii. p. 260 (1885). 
Hydrodielidon huapareia (Natt.) ; Macgill. Brit. B. v. p. 663 
(1852)- 
Hydrodielidon kybrida, 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 w-ebs ; the shafts of the 
primaries white, the outer ones with the greater part of the 
