318 LARID/, TERNS. 
prey by darting impetuously upon it, when they are usually submerged for a 
moment. The larger kinds feed principally upon little fish, procured in this way ; 
but most of the smaller ones are insectivorous, and flutter about over marshy spots 
like swallows or nighthawks. The general appearance and mode of flight have 
suggested the name of ‘“sea-swallow,” the equivalent of which is applied in nearly 
all civilized languages. A forking of the tail is an almost universal character. 
In the Caspian and marsh terns, the black tern and its allies, and some others, the 
forking is moderate, and not accompanied by attenuation of the lateral feathers ; but 
ordinarily, these are remarkably lengthened and almost filamentous, as in the barn 
swallow. It should be observed that in all such cases the narrowing elongation is 
gradual, and consequently less evident in the young ; and that it is very variable in 
its development. The noddies offer the peculiarity of a tail lightly forked centrally, 
but rounded laterally. The feet are small and relatively weak throughout the 
group; the terns walk but little, and scarcely swim at all. Ordinarily the webbing 
is rather narrow, and excised, particularly that between the middle and inner toe ; 
in Hydrochelidon, this occurs to such extent that the toes seem simply semipalmate. 
The webs are fullest in Anows, where also the hallux is unusually long; in some 
species, this toe is slightly connected with the tarsus by a web. The inner toe is 
shorter than the outer, and much less than the middle, which, especially in Hydro- 
chelidon, is much lengthened, and has the inner edge of its claw dilated, or even 
slightly serrate. The coloration is very constant, almost throughout the subfamily. 
Most of the species are white (often rosy-tinted below), with a pearly-blue mantle, 
a black cap on the head, and dark-colored primaries, along the inner web of which 
usually runs a white stripe. These dark-colored quills, when new, are beautifully 
frosted or silvered over; but this hoariness being very superficial, soon wears off, 
leaving the feathers simply blackish. The black cap is often interrupted by a white 
frontal crescent; it is sometimes prolonged into a slight occipital crest; in a few 
species, it is replaced by a black bar on each side of the head. One species, Inca 
mystacalis, has a curious bundle of curly white plumes on each side of the head. 
Another, Gygis alba, is pure white all over; Procelsterna cinerea is wholly ashy : 
the noddies are all fuliginous; the upper parts of Haliplana are dark; the species 
of Hydrochelidon are largely black. These are the principal if not the only excep- 
- tions to the normal coloration just given. ‘The sexes are never distinguishable, 
either by size or color; but nearly all the species, in the progress toward maturity, 
undergo changes of plumage, like gulls; while the seasonal differences are usually 
considerable. As a rule, the black cap is imperfect in young and winter specimens, 
and the former show gray or brown patching instead of the pure final color of the 
mantle. In all those species in which the bill is red, orange or yellow, it is more or 
less dusky in the young. The changes are probably greatest in the black terns. 
The general economy is much the same throughout the group. The eggs are laid 
in a slight depression on the ground—generally the shingle of beaches, or in a 
tussock of grass in a marsh, or in a rude nest of sticks in low thick bushes; they 
are 1-3 in number, variegated in color. Most of the species are maritime, and such 
is particularly the case with the noddies; but nearly all are also found inland. 
They are noisy birds, of shrill penetrating voice; and no less gregarious than 
gulls, often assembling in multitudes to breed, and generally moving in company. 
Species occur near water in almost every part of the world, and most of them 
are widely distributed; of those occurring in North America, the majority are 
found in corresponding latitudes in the Old World. About seventy species are 
currently reported; these must be reduced nearly one-half; the true number is 
