PASSKKKS. BIRDS. PASSKRKS. 



273 



the foot which exhibits a granular or reticulated 

 appearance, is the lower surface of the toes. The toes 

 are not furnished at the base with a distinct membrane 

 or small web, such as is usually found at this point in 

 other birds ; but, on the other hand, the outer toe of 

 each foot is generally united to the middle one for a 

 greater or less extent ; sometimes only at the base, but 

 sometimes nearly to the extremity. The claws with 

 which the toes are armed are either of moderate length 

 and strength, or very long and slender; they never 

 emulate the formidable talons of the predaceous birds, 

 nor do they degenerate into the flat scratching nails 

 characteristic of the gallinaceous birds. 



This structure of the hind limbs renders the Passeres 

 very active on their feet, whether they disport them- 

 selves amongst the branches and twigs of the trees, or 

 hop, as is their usual manner of progression, on the 

 ground. Their wings or anterior members are also 

 well developed, and they generally possess the power 

 of flight in a very high degree of perfection. In this 

 respect, indeed, we find a considerable variety amongst 

 the members of this group, some of them furnishing 

 most remarkable examples of rapid and long-continued 

 flight; others enjoying the power of moving through the 

 air with more moderation, but few deserving the char- 

 acter of being feeble flatterers. In accordance with these 

 variations in the volitant power, the form of the wings 

 also varies, being long and pointed in those which fly 

 best, and broader and rounded at the tip in proportion 

 as the power of flight diminishes ; but the number of 

 primary quill feathers in the wings is tolerably uniform, 

 being generally ten, although the first of these is fre- 

 quently very small, or even altogether wanting. The 

 quill feathers of the tail are generally twelve in number. 



The form of the bill, as may be supposed from 

 the statement already made with regard to the great 

 difference of food, is very variable ; but it is to be 

 remarked that it never partakes of the strongly-hooked 

 character which prevails in the preceding order, nor is 

 its base covered by anything like a cere. The bill is 

 ordinarily conical ; sometimes short and stout ; some- 

 times elongated and slender; in many of the long-billed 

 forms, the whole of the organ is more or less curved ; 

 and a considerable number of those with short bills 

 have the upper mandible slightly arched, and bent 

 down at the tip, near which the margins are armed 

 with small teeth. The object of these various forms of 

 the bill, and of others to which we need not refer here, 

 will be readily seen when we come to treat of the his- 

 tory of the species belonging to this order, in the classi- 

 fication of which they are also of great importance. 



With regard to the internal structure of these birds, 

 we need only state that the ossophagus is dilated into 

 a small crop ; that the walls of the stomach are very 

 thick and muscular, forming a gizzard; and that in many 

 of them the inferior larynx, situated at the point of union 



of the two bronchial tubes coming from the two sepa- 

 rate lungs, is provided with a complicated apparatus ot 

 small muscles, by the action of which the birds are 

 enabled to modulate their notes in a surprising manner, 

 so as to produce that delightful music which charms 

 the ears of all wanderers in the country throughout the 

 spring and summer. 



From the vast variety of forms included in this order, 

 and the gradual manner in which their distinctive char- 

 acters blend one with the other, the division of these 

 birds into subordinate groups presents no small diffi- 

 culties ; and the opinions of authors upon their classifi- 

 cation are almost as various as the authors themselves. 

 It is impossible for us to travel through these minutiae 

 of classification, the discussion of which, moreover, 

 would be neither interesting nor instructive to the 

 reader; the system here followed is nearly identical 

 with that of Mr. G. R. Gray, which in its turn is 

 founded upon that of Cuvier. The latter great natu- 

 ralist divided his order of passerine birds into five great 

 families, to which he gave the names of Dentirostres, 

 Fissirostres, Conirostres, Tenuirostres, and Syndactyli; 

 the first four being characterized by peculiarities in the 

 conformation of the bill, and the last by the structure 

 of the feet, the outer toe in each foot being united to 

 the middle one throughout nearly the whole of its length. 

 Of the birds thus distinguished, the majority are now 

 generally admitted to be nearly allied to those forming 

 Cuvier's group of the Fissirostres, with which they may 

 well be associated in a single tribe or suborder ; the 

 remainder (the Hornbills) approach the Crows in their 

 general structure, and may be placed with them in the 

 tribe of Conirostres. This leaves four divisions which 

 may be briefly characterized as follows : 



1. FISSIKOSTRES, with the bill usually more or less 

 depressed at the base, and the gape wide, opening as 

 far back as the eyes see Plates 5 to 7. 



2. TENUIROSTRES, with the bill much elongated and 

 slender, and the gape not so wide as in the preceding 

 group see Plates 8 and 9. 



3. DENTIROSTKES, with the upper mandible more 

 or less curved, hooked at the tip, and armed with a 

 single tooth on each side see Plates 10 and 11. 



4. CONIROSTRES, with a stout and usually straight 

 conical bill, in which the upper mandible is either 

 smooth at the edges or toothed throughout see Plates 

 12 and 13. 



It is to be observed, however, that the characters 

 above given are only to be regarded as appertaining to 

 the groups generally ; as from the gradual passage of 

 the one into the other, it sometimes becomes necessary, 

 in order to avoid violating evident affinities, to place a 

 given bird rather arbitrarily in the group to which it 

 belongs by its general characters, although it may 

 not distinctly present those expressed in the name of 

 the group. 



VOL. I. 



2M 



