15G AYES. 



The bony tail is very short, [and consists in most instances of nine vertebra;, the 

 tliree last of whicli are commonly ancliylosed into a plough-share form, and are gene- 

 rally collectively styled the coccyd], but has a range of strong feathers, which, when 

 spread out, assist in supporting the bird : their numljcr is ordinarily twelve ; sometimes 

 fourteen, and in many of the Gii/litiiicra; eigliteen ; [in some few genera, as the 

 Grebes, Nandou, &c., tliese are wanting altogetlier ; a single Humming-bird {Troclii/us 

 ciiiciinis) possesses only six ; the Ani eight ; the rest of the Hunmiing-birds, and 

 various others, ten ; wliile the Swans present from eighteen to twenty-two. The t\A0 

 central of these feathers are implanted above the even line formed bv the insertion of 

 the rest, and essentially eorresj)ond to the wing-tertiaries, as the others do to the 

 wing-secondaries ; the latter being in no instance moulted more than once in the year, 

 tlie former in many instances twice : we might accordingly designate the two central 

 tail feathers, wliicli differ conspicuously from the rest in structure, uropi/r/iuls. Aboye 

 and below the tail are lengthened featliers, commonly of weak texture, known as the 

 vpper and under tail-coverts. 



The rest of the featliers of Birds arc named from their position, as frontal, coronal, 

 ciccij)ital, nuchal, dorsal or hitei-scapulanj, which togellier iorm a contiuutjus series, apart 

 from the scapalaries ,■ tliose in front of the eye are teruied loral, and tlic auditory ajjerture 

 is covered bv a range styled auriculars or ear-coverts : tlie sides of the neck and medial 

 ]iortion of the sternal and abdominal rej^ion are at most covered ■with down ; the 

 former being concealed by the lateral feathers of tlie f^re and hind neck meeting ; the 

 bitter by a similar junction of two distinct lateral ranges. As it is necessary that the 

 warm body of a bird should be in actual contact with tlie eggs during incubation, 

 wb.'itever down may cover the medial inferior region disapj/cars in the females towards 

 the season of propagation, even in tliose confined in cages, so that this bareness is not 

 produced mechanically. Finally, besides various accessory tufts in different genera, 

 some long slender feathers are situate at the base of the wing interually, which are 

 named axillarics] . 



The legs hare a femur, a tibia, and a peronfcum attached to the femur with a spring, 

 which maintains their extension without eif'ort on the part of the muscles. The tarsus 

 and metatarsus are represented by a single bone, terminating below in three pullies. 



Most commonly there are three toes belbre, and a thumb behind* ; tlie latter being 

 sometimes deficient. In the Swifts it is directed forwards, [though half-reversible : in 

 the Moth-hunters and some others, inward, at a right angle with the axis of the body]. 

 in the yoke-footed Birds, on tlie contrary, the external toe and the thumb are dis- 

 posed backwards [most usually, but sometimes (as in the Touracos and Puff-birds) 

 laterally : in the Trogons, the iir.-t and second toes are opposed to the third and 

 fourth; and accordingly the longest toe, or that which corresponds to the middle one 

 in the generality of the class, is intrard , instead of being outivard, as in all the other 

 yoke-footed grou]]s]. The number of articulations increases in each toe. commencinn" 

 with the thumb, which has two, and ending with the external toe, which has five. 

 [The Swifts present a remarkable exception ; and it may be remarked that, in the 

 Ostrich alone, only two toes are ]iresent.] 



In general, [invariably]. Birds are covered with feathers, a sort of tegument best 



