EXTERNAL PARTS OF BIRDS. — TOPOGRAPHY. 99 



limited by the hip-joint. The rib-bearing extent of the back-bone, ribs themselves, and the 

 greatly enlarged breast-bone (Lat. sternum') compose the cavity of the chest (Lat. thorax). 

 Upon this bony box, which contains the heart and lungs and some other viscera, are saddled 

 on each side the bones of the shoulder -girdle or scapular-arch, namely, the shoulder-blades 

 (Lat. scapula), the coracoids, and the collar-bones (Lat. clavicula), all three of which come 

 together at the shoulder-joint. The thoracic cavity is not separated by any partition or dia- 

 phragm from that of the belly (Lat. abdomen) , which with the 2}elcis, or basin, contains the 

 digestive, urinary, and genital organs. The pelvis is composed, in dorsal mid-line, of so many 

 vertebra? (dorso-lnmhar, sacral proper, and urosacral, as become immovably joined to one 

 another, and laterally of the confluent haunch-bones. The numerous anchylosed (or confluent) 

 vertebrfe compose the sacrum. The haunch-bones or ossa innominata consist on each side of 

 three bones, ilium, ischium, and pubis, in adult life more or less perfectly anchylosed. Where 

 they all three come together on each side is the hip-joint or coxa. The remaining bones, 

 usually included among those of the body proper, are the coccygeal or caudal vertebrae. (For 

 anatomical detail see beyond, under Osteology, etc.) 



Topography of the Body. — Besides being thus divided into head, neck, trunk, and 

 members, the exterior of the body is further subdivided or mapped out into regions for purposes 

 of description. It is necessary for the student to become familiar with the " topography" of a 

 bird, as this kind of mapping out may be called, for names of regions or outer areas are inces- 

 santly used in ordinary descriptive oraithology. Many more names have been applied than are 

 in common use; I shall try to define and explain all those which are usually employed, begin- 

 ning with the parts of the body, and ending with those of the members. 



1. REGIOXS OF THE BODY. 



Upper and Under Parts. — Draw a line from corner of mouth along side of head and 

 neck to and through shoulder-joint and thence along side of body to root of tail ; all above this 

 line, including upper surfaces of wings and tail, are upper parts ; all below it, including under 

 surfaces of wings and tail, are under parts ; for which the short words "above" and "below" 

 often stand. The distinction is arbitrary, but so convenient as to be practically indispensable. 

 It will be seen how an otherwise lengthy description, enumerating parts that lie over or under 

 the " lateral line," can be put in so few words as, for example, " above, green; below, yellow." 

 Many birds' colors have some such simple general distribution. These parts are also dorsal 

 (Lat. dorsum, back) and ventral (Lat. venter, belly) surfaces or aspects. Upper parts of the 

 body proper, or trunk, have also received the general name of notceum (Gr. vojtos, notos, back) ; 

 under parts, similarly restricted, that of gastrceum (Gr. yaarrip, gaster, belly) . but these terms 

 are not much used. These two are never naked, while both head and neck may be variously 

 bare of feathers. The only exception is the transient condition of certain birds during incuba- 

 tion, when, like the Eider Duck, they pull ofl" feathers to furnish the nest, or when the plumage, 

 as usually happens, wears off. The gastra?um is rarely ornamented with feathers different in 

 texture or structure from those of the plumage at large ; but such a case is furnished by Lewis' 

 woodpecker (Asyndesmus torquatus), and much more notable cases are those of certain Birds of 

 Paradise, Storks, etc. The notaeum, on the contrary, is often the seat of extraordinary devel- 

 opment of feathers, either in size, shape, or texture, or all three of these qualities ; as the sin- 

 gularly elegant dorsal plumes of many Herons. Individual feathers of the notseuni are Tnustly 

 pcnnaceous, straiglit, lanceolate; and as a whole lie smoothly shingled or imbricated. The 

 ventral feathers are usually more largely plumulaceous, and less flat and imbricated, but even 

 more compact — that is, thicker — than those of the upper parts ; especially among water birds, 

 where they are more or less curly, and very thick-set. There are subdivisions of the 



