138 GENERAL ORNITHOLOGY part ii 



(or confluent) vertebrae 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' is the hip-joint. The remaining bones, usually 

 included among those of the body proper, are the coccygeal or caudal 

 vertebrae. (For anatomical details 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 the purposes of description. 

 It is necessary for the student to become familiar with the " topo- 

 graphy " of a bird, as this kind of mapping out may be called, for 

 the names of the regions or outer areas are incessantly used in 

 ordinary descriptive ornithology. Many more names have been 

 applied than are in common use ; I shall try to define and explain 

 all those which are usually employed, beginning with the parts of 

 the hody, and ending with those of the members. 



1. Begions of the Body. 



Upper and Under Parts. — Draw a line from the corner of the 

 mouth along the side of the head and neck to and through the 

 shoulder-joint and thence along the side of the body to the root 

 of the tail ; all above this line, including the upper surfaces of the 

 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 

 purely arbitrary, but so convenient as to be practically indispens- 

 able. 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' colours have some such simple general distribution. 

 These parts are also the dorsal (Lat. dm'sum, back) and ventral (Lat. 

 venter, belly) surfaces or aspects. The upper parts of the body 

 proper, or trunk, have also received the general name of notcewm 

 (Gr. vcSrosj, notos, back) ; the under parts, similarly restricted, that 

 of gastrmum (G-r. yaa-r-qp, 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 incubation, when, hke 

 the eider-duck, they pull off feathers to furnish the nest, or when 

 the plumage, as usually happens, wears off. The gastrseum 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's woodpecker {Asyndesmus torquatus). The notseum, on 

 the contrary, is often the seat of extraordinary development of 



