EXTERNAL PARTS OF BIRDS. — TOPOGRAPHY. 101 



which meet over the rump. The whole of notaeum, taken together with upper surfaces of wings, 

 is called the mantle (Lat. stragidum, a cloak); often a convenient term, as in describing Gulls 

 and Terns, for example. In like mauuer, the 



Gastraeum is subdivided into regions, called breast (Lat. pectus; fig. 25, 24), belly (Lat. 

 abdomen; fig. 25, 1.8), and sides of body (Lat. pleura ; fig. 25, 2'S). The "sides" or pleurae 

 belong as much to dorsal as to ventral aspects of a bird's body ; but in consequence of the un- 

 derneath-freighted shape, the line we drew passes so high up along them, that they are almost 

 entirely given over to gastraeum. The breast begins over the merry-thought where jugulum 

 (see beyond) ends; on either hand, it slopes up to "sides"; behind, its extension is indefinite. 

 It should properly reach as far as the breast-bone does, to the limit of the thorax; but iu many 

 birds this would leave almost nothing for abdomen, and the limit would fluctuate with almost 

 every family of birds, the sternum being so variable in length. Practically, therefore, without 

 reference to the breast-bone, "breast" or pectus is restricted to the swelling anterior part of 

 gastraeum, which we call belly or abdomen as soon as it begins to straighten out and flatten. 

 Abdomen, like pectus, rounds up on either hand into sides; behind, it ends in a transverse line 

 passing across the anus. It has been unnecessarily divided into epigastrium or "pit of the 

 stomach," and venter or lower belly; but these terms are rarely used. (^Crissum is a frequent 

 name of some indefinite region immediately about the vent ; sometimes meaning flanks, some- 

 times vent-feathers or under tail-coverts proper; I refer to it again in connection with these 

 last.) Thougli these boundaries seem fluctuating and not perfectly satisfactory, a little practice 

 will enable the student to appreciate their proper use in descriptions, and to employ them him- 

 self with sufficient accuracy. The adjectival terms are respectively pectoral, abdominal, and 

 lateral. The anterior continuation of the trunk, or the 



Neck (Lat. colliim) is likewise subdivided into regions. Its lateral aspects, except in birds 

 that have lateral neck-tracts of feathers, are formed by the meeting over its sides of feathers 

 that grow on dorsal and ventral pterylae, the skin being usually not planted with feathers on its 

 sides. Partly on this account, perhaps, a distinct region is not often named ; we say simply 

 " sides of neck," or " neck laterally" {parauchenia, fig. 25, 9). The neck behind, or its dorsal 

 (upper) aspect, is divided into two portions : a lower, " hind neck " proper, or " scruff of neck " 

 (Lut. cervix; fig. 25, 8), next to back ; and an upper, or " nape of neck " (Lat. nucha; fig. 25, 

 7), adjoining hind head. These are otherwise respectively known as the cervical and nuchal 

 region; and, in speaking of both together, we usually say "neck behind." The front of the 

 neck lias been needlessly subdivided, and these subregious vary with almost every writer. It 

 suffices to call it throat (Lat. gula, fig. 25, 37, or jugulum, 34); remembering that Xhe jugular 

 portion is lowermost, vanishing in breast, and the gula uppermost, running into chin along 

 under surface of head. Guttur is a term sometimes used to include gula and jugulum together: 

 it is equivalent to "throat," as just defined; the adjective is guttural. Though generally cov- 

 ered with feathers, the neck is frequently naked in part. When naked behind, it is usually 

 cervix that is bare, as so characteristically occurs in Herons, from interruption of forward ex- 

 tension of pteryla spinalis. Nucha is seldom if ever naked, except as an extension of general 

 bald-headedness. Gula is similarly naked from above downward, as conspicuously illustrated in 

 the order Steganopodes, comprising Pelicans, Cormorants, etc., which have a bare gular pouch; 

 and as seen in many Vultures, whose baldness extends over nucha and gula, and even all 

 around the neck, as in the Condor, whose nakedness ends with so singular a collar of close-set, 

 downy feathers. The lower throat or jugulum becomes naked in a few birds, in which a dis- 

 tended crop or craw protrudes, pushing apart feathers of two branches of pteryla ventralis as 

 these ascend the neck. The rule is, that the neck is not the seat of enlarged or otherwise highly 

 developed feathers, which might restrict the requisite freedom of its motion; but there are some 



