VARIOUS rOEMS OF BILLS. 25 



convenieut incidental terms in general descriptions. Various other lesser 

 terms, expressing special modifications, as lamellirostral, acutirostral, etc., 

 are employed ; but all are best used, now, as common, not as proper names, 

 simply descriptive of 



§ 47. Other Forms. A bill is called long, when notably longer than the 

 head proper ; short, when notably shorter ; medium, in neither of these con- 

 ditions. It is compressed, when higher than wide, at the base at least, and 

 generally for some portion of its length ; depressed, when wider than high ; 

 terete, under neither of these conditions. It is recurved, when curved up- 

 ward ; decurved, when curved downward ; bent, when the variation in either 

 direction is at an angle ; straight, when not out of line with axis of the head. 

 A bill is obtuse (said chiefly of the paragnathous sort) when it rapidly 

 comes to an end that therefore is not fine ; or when the end is knobby ; it is 

 acute when it runs to a sharp point ; acuminate, when equally sharp and slen- 

 derer ; attenuate, when still slenderer; subulate (awl-shaped), when slen- 

 derer still; acicular (needle-shaped), when slenderest possible, as in some 

 humming-birds. A bill is arched, vaulted, turgid, tumid, inflated, etc., 

 when its outlines, both crosswise and lengthwise, are notably more or less 

 convex; and contracted, when some, or the principal, outlines are concave 

 (said chiefly of depressions about the base of the upper mandible, or of con- 

 cavity along the sides of both mandibles). A bill is hamulate (hooked) or 

 unguiculate (clawed), when strongly epiguathous, as in rapacious birds, 

 where the upper mandible is like the talon of a carnivorous beast ; it is den- 

 tate, when toothed (§ 46), as in a falcon; if there are a number of sim- 

 ilar " teeth," it is serrate (like a saw) ; it is cultrate (knife-like) when ex- 

 tremely compressed and sharp-edged, as in the auk, skimmer ; if much 

 curved as well as cultrate, it is fcdcate (scythe-shaped) ; and each mandible 

 may be oppositely fiilcate, as in the cross-bill. A bill much flattened and 

 widened at the end (rare) is spcUulafe; examples : spoonbill, shoveller duck. 

 One is called lamellate, when it has a series of plates or processes just inside 

 the edges of the mandibles ; as in all the duck order, and in a few petrels ; 

 the design is to furnish a sifter or strainer of water, just what is effected in the 

 whale, by the "bone" in its mouth. Finallj^ the fiir end of the bill, of Avhat- 

 ever shape, is called the tij) or apex (fig. 5, n) ; the near end, joined to the 

 rest of the skull, the base; the rest is the continuity. Some other featui-es 

 of the bill as a whole are best treated under separate head of 



§ 48. The covering of the bill, (a.) In the great majoritj- of birds, 

 including nearly all perchers, many walkers and some swimmers, the sheath- 

 ing of the mandibles is wholly Jiard, horny or corneous; it is integument 

 modified much as in the case of the nails or claws of beasts. In nearly all 

 waders and most swimmers, the sheath becomes, wholly or partly, softer, and 

 is of a dense, leathery texture. But some swimmers, as among the auks, 

 furnish bills as hard-covered as any, while some perchers have it partly quite 

 soft, so that no unexceptional rule can be laid down; and, moreover, 

 the gradations from one extreme to the other are insensible. Probably, 



KEY TO N. A. BIRDS. 4 



