253 



Order V. GAVLE. 



Family LABIDiE. 



Subfamily STEBNINJE. 



Genus STERNA. 



Sterna, Brisson, Orn. vi. p. 202 (1760). 



Thalasseus apud Boie, Isis, 1822, p. 563. 



Sternula apud Boie, Isis, 1822, p. 564. 



Viralva apud Stephens in Shaw's Gen. Zool. xiii. pt. 1, p. 174 (1825). 



Thalasscea apud Kaup, Natiirl. Syst. p. 97 (1829). 



Actochelidon apud Kaup, op. cit. p. 31 (1829). 



Hydroprogne apud Kaup, op. cit. p. 91 (1829). 



Sylochelidon apud C. L. Brehm, Vog. Deutschl. p. 769 (1831). 



Helopus apud Wagler, Isis, 1832, p. 1224. 



Planetis apud Wagler, torn. cit. p. 1222. 



Haliplana apud Wagler, torn. cit. p. 1224. 



Onychoprion apud Wagler, torn. cit. p. 1277. 



Laropis apud Wagler, torn. cit. p. 1225. 



Hydrochelidon apud Bonaparte, Comp. List, p. 61 (1838). 



Hydrocecropis apud Boie, Isis, 1844, p. 179. 



Thalassipora apud Biippell, Syst. Uebers. p. 140 (1845). 



Anous apud Lesson, Descr. Mamm. et Ois. p. 255 (1847). 



The Terns, although closely allied to the Laridaa, form a fairly separable subfamily, containing 

 two genera, which inhabit the Western Palsearctic Begion. Of these the genus Sterna is repre- 

 sented in all the zoogeographical regions into which the world has been divided, nine species 

 being found in the Western Palsearctic Begion. These birds are remarkable for their buoyant, 

 wavering, and swiftly gliding flight, from which their name Sea-Swallows is not inaptly derived. 

 Owing to their short feet, they do not walk well, but are especially strong on the wing, and swim 

 also with ease and elegance, sitting on the water as lightly as a feather. They feed on Crustacea, 

 small fish, aquatic insects, &c, which they procure chiefly by picking them up from the 

 surface of the water whilst hovering just high enough above to be able to dip into it; or some- 

 times they will hover at some little altitude and suddenly plunge down and pick up their food. 

 They are sociable — being usually found in small flocks, and even breeding in company with 

 others of their own species, — and are noisy, frequently uttering their somewhat harsh scream. 

 They frequent the sea-coasts, or occasionally the shores of lakes, and breed in these localities, 

 their nest being a mere depression in the sand near the edge of the water. Their eggs are 



2IO 



