LARIDA. — GENERA. 195 
joined to the form of the neck, renders it probable that 
they dart upon their prey something in the same man- 
ner as is done by the herons. Of two species already 
known, one is stated to inhabit both the East and West 
Indies, but this is somewhat doubtful. 
(216.) The Larip#, or gulls, constitute a much 
more numerous family than either of the three last. 
Their structure is also more perfect, in a general sense, 
although inferior in that particular construction which 
constitutes the perfection of the order, namely, the 
power of swimming and diving. The wings are very 
long; and the feet, although webbed, enable these 
birds to walk about with perfect ease on the shore, in 
search of food: the hind toe is very small, some- 
times wanting ; but the legs are nearly as long as 
in some of the wading birds, of which they are the 
representatives : the bill is slender, much compressed, 
and is gradually, but not abruptly, bent. Gulls are 
well known to be gregarious, frequently associating 
in large flocks, and devouring every description of 
animal and vegetable.food: they swim with tolerable 
facility, but cannot dive well: their power of flying 
is very great, for many races are almost constantly upon 
the wing, and they brave the most violent storms. . 
Most of the genera are universally distributed. 
(217.) The genera may be noticed in the following 
order : — The terns, or sea-swallows (Sterna), con- 
stitute the fissirostral type: they have remarkably long 
wings and slender bills; the tail is forked ; and the 
plumage generally is of a delicate pearl white, with 
more or less black upon the head: the species are 
numerous, and occur in both hemispheres. The extra- 
ordinary genus, Rhynchops, or skimmer, although 
possessing much of the general habits of the terns, is 
eminently distinguished by the singular form of its 
bill (Vol. I. p. 72.), the upper mandible of which is 
considerably shorter than the under, and appears as if 
one third of the length had been broken off: three 
species have been described, to which we now add 
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