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[Case 26,] 
48 BIRD GALLERY. 
species are exhibited, one of the most noteworthy being the Pacifie Gull 
(Gabianus pacificus) (411), with its remarkably stout bill ; while Tschudi’s 
(430), Hemprich’s (431), and Heerman’s (429) Gulls are specially inter- 
esting forms on account of their peculiar dusky coloration. The hooded 
Gulls comprise such species as our Black-headed Gull (L. ridibundus) 
(432), the commonest British species, and the Bonaparte’s (L. philadel- 
phie) (484), Mediterranean Black-headed (L. melanocephalus) (435), 
Great Hooded (L. ichthyactus) (486), and Little Gull (L. minutus) (431), 
all accidental visitors to Britain. In these birds the black hood is only 
assumed during the breeding-season, at other times the head is white or 
nearly so, Sabine’s Gull (Xema sabinei) (438) and the very rare Ross’ 
Rosy Gull (Rhodostethia rosea) (489) are aberrant forms; in the former 
the tail is forked, in the latter cuneate or wedge-shaped. Both belong to 
the Arctic Seas and are only stragglers to our coasts. 
The Terns or Sea-Swallows may be recognised by their nearly straight. 
pointed and comparatively slender bill, forked tail, and more slender 
build. Specially mteresting forms are the White Tern (Gygis candida) 
(440) and the Noddy (dnous stolidus) (443), with its curious nest of 
mud and seaweed, ete. placed on the bough of a tree. This bird has twice 
been recorded from our shores. In the British Islands five species of Tern 
(Sterna), viz.: the Common (S. fluviatilis) (452), Arctic (S. macrura) 
(453), Little (S. minuta) (448), Sandwich (S. cantiaca) (455) [ Pl. VIII}, 
and Roseate (S. dougalli) (454), are regular summer visitors and 
remain to breed, the latter being very much the rarest. Besides these, 
seven other species of Tern have been recorded as accidental visitors, 
viz. : the Sooty (S. fuliginosa) (446), Bridled (S. anestheta) (441), 
Caspian (Hydroprogne caspia) (456), Gull-billed (Gelochelidon anglica) 
(457), White-winged (Hydrochelidon leucoptera) (458), Whiskered 
(H. hybrida) (459), and Black (H. nigra) (460). All these are repre- 
sented in the Case, and the last-named may be considered a regular 
visitor and formerly bred in England. 
The most remarkable members of the family are the Scissor-billed 
Terns, of which an example will be found in Rhynchops flavirostris (462). 
They have been given their trivial name on account of the peculiar 
form of the bill, which is quite unique among birds. Both upper and 
lower mandibles are compressed to a knife-like thinness, and the lower 
is produced beyond the upper for a considerable distance. This peculiar 
modification appears to be for the purpose of catching fishes from 
among the surface-swimming shoals. The lower jaw being used as a 
sort of plough, catches up the prey as the bird flies along over the 
surface. Five species are known, of which one is Asiatic, one African, 
and three are American. 
