14 HEAD, NECK, BODr. 



§ 31. Head has the general shape of a 4-sided p^^ramid; of which the 

 base is applied to the end of the neck, and does not appear from the exte- 

 rior; the uppermost side is more or less convex or vaulted, sloping in every 

 direction, and tapering in front; the sides proper are flatter, more or less 

 perpendicular, and taper in front ; the bottom is likewise flattish and simi- 

 larly tapering. The departures from this typical shape are endless in degree, 

 and variable in kind ; they give rise to numerous general descriptive terms, 

 as "head flattened," "head globular," etc., but these are not susceptible of 

 precise definition. The sides present each two openings, eyes and ears; 

 their position is variable, l)oth absolutely and in respect to each other. But 

 in the vast majority of birds, the ej'es are strictly lateral, and near the mid- 

 dle of the side of the head, while the ears are behind and a little below. 

 Exceptions : — owls have eyes "anterior;" woodcock and snipe have ears be- 

 low and not behind the eyes. The mouth is always a horizontal fissure in 

 the apex of the cone ; there are no other openings in the head proper, for 

 the nostrils are always in the bill. The 



§ 32. Neck, in eflect, is a simple cylinder : rendered somewhat hour- 

 glass shaped as above stated. Its length is variable, as is the number of 

 bones it has. Bearing the head with the bill, M'hich is a bird's true hand, it 

 is wxmsu'CiWy flexible, to permit the necessarily varied motions of this impor- 

 tant organ. Its least length may be said to be that which allows the point 

 of the bird's beak to touch the oil-gland on the rump ; its length is usually 

 in direct proportion to length of legs, in obvious design of allowing the 

 beak to touch the ground easily to pick up food. Its hal)itual shape is a 

 double curve like the letter S ; the lower belly of the curve fits in the space 

 between the legs of the merry-thought (furcula) ; the upper limb of the 

 curve holds the head horizontal. This sigmoid flexure (sigriui, Greek S) is 

 produced by the shape of the jointing surfaces of the several bones : it may 

 be increased, so that the upper end touches the lower belly; may be de- 

 creased to a straigiit line, but is scarcely carried beyond this in the opposite 

 direction. As a generalization, the neck may be called longest in wading 

 birds; shortest in perching birds; intermediate in swimming birds; but 

 some waders, as plovers, have short necks; and some swimmers, as swans, 

 extremely long ones ; a very long neck, however, among perching birds is 

 rare, and confined mainly to a crane-like African hawk, and certain of the 

 lowest perchers that stand on the confines of the waders. The shape of the 



§ 33. Body proper or trunk (L. truncus), is obviously referable to that 

 of the egg; it is ovate, (L. ovimi, an egg). The swelling breast muscles 

 represent the but of the &g^, which tapers backwards. But this shape is 

 never perfectly expressed, and its variations are unnumbered. In general, 

 perching birds have a body the nearest to an oval; among waders, the oval 

 is usually compressed, or flattened perpendicularly, as is well seen in the 

 heron family, and still better in the rail family, where the narrowing is at 

 an extreme ; among swimmers, the body is always more or less depressed, 

 or flattened horizontally, and especially underneath, to enable these birds to. 



