PASSERIN.E. 195 



cliiefly in the air, [even copulating on the wing], and pursue insects in flocks, sometimes at a great 

 altitude, uttering discordant screams. Tliev nestle in the holes of walls and rocks, and climb perpen- 

 dicidar surfaces with facility. 



[With this genus, we enter upon a very different ty])c of form from any of the foregoing. The 

 entire anatomy, if we except the trachea and toes, and the latter more tlian any other genus, very 

 closely rcsendjles that of the Humming-birds. It is only iu superficial or adaptive modifications that 

 they accord with the Swallows. The lower larynx is furnished with only one pair of muscles, the ordinary 

 sterao-f racheak'S ; there are immense salivary glands, as in the Humming-birds, which secrete a viscid 

 mucus, and no intestinal cceca ; the clothing feathers have a considerable supplementary plume. 



It is necessary to subdivide them into 



The True Savifts (C'jjjsehis, as restricted) — 

 Which have a forked tail, and feet as already described. 



Of several species, two only inhabit Europe.] 



Tlie Common SwUt (Hinrndo apiis, Lin.; C murar'ui.s, Tem.) — Black, with a white throat, [and common 

 throu;^bout Europe in summer, making- but a short stay. Tlie young- do not moult before the second autuuni.] 



The "White-belhed Swift (//. tjtelba, Lin). — Larger, and brown, with white collar and medial inferior reg-ion. [Of 

 rare occurrence in Britain. Unlike the Swallows, these birds rear but one brood in a season. There are several 

 more.] 



Others have stiff, pointed tail-feathers, as in 1he AVoodpeckcrs, and the thimdj dh-ec ted backward ; 

 hut they pass insensibly into the preceding. They constitute the 



Ch.ktura, Swainson. 



There is one common in North America, the Chimneij Swallow of AVilson ; also others in the eastern hemisphere, 

 one or more of which inhabit Australia. 



The Truj-: Swallows (Ilirundo, Cuv.) — ■ 

 Have the feet and sternum similar to those of ordinary Pasficrina ; [also the complex inferior larynx 

 as usual, small caeca to the intestine, twelve lail-feathers, 6ic. Their rapid flight depends entirely on 

 external modifications, for which reason it is much less capable of protraction than in the Swifts, as is 

 particularly shown by their weariness after performing migration, on which occasions they have been 

 seen to alight fiat upon the sea.] 



Some have the feet feathered to the claws, have a slight tendency to revert the posterior toe, and a moderately 

 forked tail ; as 



The Jlartin Swallow {//. urliica, Lin.). — Glossy black above, white below and on the rump. Every one is 

 acquainted with the solid mud-built nest of this species, fixed untler window-eaves, the juttine; roofs of houses, Sjc. 



Others ha\-e naked feet, and a more sharply forked tail, the exterior feathers of which are often much 

 prolonged. As 



The Chimney Swallow (//. rustka, Lin.). — Above [and across the breast] glossy black, the forehead and throat 

 rufoQS, beneath [and a spot on each except the middle tail-feathers], white : it builds generally in chimneys. 



The Bank Swallow (//. riparin, Lin.). — Brown above and across the breast, the throat and under-pai'ts white. 

 fA small tuft of down on each foot.] It burrows and fomis its nest in steep banks. [There are two others in 

 southern Europe, H. rvfula^ Tem., or H. daurica, Sav., and H. rvpesiris, Liu.] 



Among the [very numerous] species foreign to Europe, may be noticed a very small one from the Indian Archi- 

 pelago, the //. csciilcnto, Lin., which is brown above, whitish below and at the tip of its forked tail. It is cele- 

 brated for its nest, formed of a whitish gelatinous substance arranged iu layers, and obtained by macei-ating [in 

 the stomach] a peculiar species of facus. The nutritious qualities attributed to these nests in China ha\e ren- 

 dered them an im]iortant article of traffic in that country. 



[It is interestingto note that the Purple Swallow {H. purpurea) of America, which has a stouter beak than the 

 others, feeds much on berries, at least while in its winter quarters, as observed by M. Audubon. The relation of 

 this genus to the Pliibalures has been already remarked]. 



The Moth-hunters [Cajirhunlijm, Lin.) — 

 Have the same light, soft plumage, minutely mottled with grey and brown, that characterizes other 

 night-birds. Their eyes are large ; the beak, still more deeply cleft than in the Swallows, and 

 [generally] armed with strong vibrissse, is capable of engulphing the largest insects, which are retained 

 bv means of a glutinous saliva, [as in the Swifts] ; the nostrils, placed at its base, are like small 

 tubes ; their wings are lengthened ; the feet short, with plumed tarsi, and a membrane connecting the 

 basal portion of the toes; the thumb itself is thus connected with the internal toe, and is directed 



o 2 



