262 A VES ORDER LARIFORMES. 



are difficult to distinguish on the ground. This is especially the case with 

 the eggs of the lesser tern (Sterna minuta). 



One of the rarest visitors to Britain is the sooty tern (Sterna fuliginosa). 

 This is the species which breeds in such enormous numbers on certain islands, 

 such as Laysan in the Pacific, and Ascension Island in the Atlantic. In the 

 latter the assemblage of these birds is known as " Wideawake Fair." On 

 Ascension, according to Mr. Howard Saunders, the sooty terns lay but one 

 egg, and this was also found to be the case by Mr. Palmer on Laysan, the 

 birds being perfectly fearless, and not moving off their nest, but pecking and 

 biting at anyone that approached them. As many as two hundred dozens of 

 eggs have been collected on Ascension Island in the course of a morning, 

 and this will give some idea of the numbers frequenting that spot. 



In the tropical islands of the southern oceans is found a curious form of 

 tern, snowy-white in plumage, with a pointed black bill. This is the snowy 

 tern (Gyyis alba), which possesses a very wide range over the islands of the 

 Pacific and South Atlantic. It lays but a single egg, which is placed carelessly 

 among the rocks or scrub, but is also often found in a cavity of a branch or 

 on the fork of a tree. 



These curious river terns are called scissor-bills, on account of the remark- 

 able disparity in the length of the two mandibles of the bill and their 

 extreme sharpness of the ridges, which is compressed like the 

 The Skimmers. blade of a pair of scissors. The name given to the American 



Sub-family species by one of the old writers in 1731 is "cut-water," 

 RhynchopinoR. a very good title for the bird, as these scissor-bills fly along 

 the top of the water, cutting the latter with their blade-like 

 under mandible, which is considerably longer than the upper one. The 

 skimmers frequent rivers in the tropical countries of the Old and New 

 Worlds, being found nesting as far north as Virginia in North America, and 

 Egypt in the Old World. The eggs, which resemble those of the true terns, 

 are laid on sand-banks in the rivers frequented by the birds. Five species 

 are known, each with a separate range, Hkyncliops niyra, being found in the 

 Southern United States to Central America, _R. intercedens in Brazil, and .B. 

 melanura in the northern part of South America. R. flai'irostris is an in- 

 habitant of Africa, and R. albicollis of India. 



Their heavy build and square tails, as a rule, distinguish gulls from terns, 



but it must be remembered that some of the gulls are small, and many are 



not so big as the Caspian tern, for instance. The forked tail 



The Gulls. of the terns is seen in one genus of gulls, Xema, which con- 



Sub-family tains two species, Sabine's gull (X. sabinii), and the large 



Larince. fork-tailed gull (X. furcata). The former is an inhabitant 



of the Arctic Seas, but sometimes straggles as far as the coasts 



of Britain, while X. furcata is only known from the Galapagos and the coasts 



of Western America. Ross's gull (Wiodoxtcthia rosea) is another Arctic 



species, which on rare occasions visits Europe, but is one of the rarest of all 



the gulls, and is remarkable for its wedge-shaped tail and the beautiful rosy 



blush on its white breast, which is like that seen in the roseate tern. 



Of the true gulls (Larus), of which the common gull (L. camts) may be 

 considered the type, there are more than forty species known, and these are 

 distributed , like the terns, throughout the greater part of the globe, from the 

 Arctic regions in the north to the extreme south. The gulls may be divided 

 into two groups, those with a hood and those without. The hooded gulls 

 comprise such species as our black-headed gull (Larus ridibundus) and its 



