140 GENERAL ORNITHOLOGY part ii 



and their limits are not precisely defined ; the feathers of both are 

 of the pteryla dorsalis. In general, we should call the anterior two- 

 thirds or three-fourths of notseum "back," and the rest "rump." 

 With the former are generally included the scapular or shoulder- 

 feathers, scapulars or scapularies ; these are they that grow on the 

 pterylcB humerales. The region of notseum they represent is called 

 the scapulare, and that part of notseum strictly between them is 

 called the interscapulare (Fig. 35, 10); it is often marked, as in the 

 house sparrow, with streaks or some other distinctive coloration. 

 A part of dorsum, lying between interscapulare and uropygium, is 

 sometimes recognised as the " lower back " (Lat. tergum) ; but this 

 distinction is not practically useful. To uropygium probably also 

 belong the feathers of the pterylce femorales, or at any rate these are 

 commonly included with the rump in descriptions ; but they more 

 properly represent the flanks (Lat. ilia, or hypochondria) ; that is, 

 sides of the rump. They are sometimes the seat of largely 

 developed or otherwise peculiarly modified feathers, as the snowy 

 flank-plumes of the white-bellied swift {Panyptila saxatilis) or violet- 

 green swallow {Tachycineta thalassina), which meet over the rump. 

 The whole of notseum, taken together with the upper surfaces of 

 the wings, is called the mantle (Lat. stragulum, a cloak) ; often a 

 convenient term, as, for example, in describing gulls and terns. In 

 like manner, the 



Gastrseum is subdivided into regions, called, in general terms, 

 breast (La.t. pectus ; Fig. 25, 24), belly (Lat. abdomen; Fig. 25, 18), 

 and sides of the body (Lat. pleurce; Fig. 25, 23). The "sides" or 

 pleurae belong really as much to the dorsal as to the ventral aspects 

 of a bird's body ; but in consequence of the underneath-freighted 

 shape, the line we drew passes so high up along them, that they 

 are almost entirely given over to gastraeum. The bi-east begins over 

 the merrythought 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 in many birds this would leave almost nothing 

 for abdomen, and the limit would moreover 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 gastrseum, 

 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 definitely 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 word constantly used for some in- 

 definite region immediately about the vent; sometimes meaning 



