106 GENERAL ORNITHOLOGY. 



fj-fTu, meta, witli, beside, etc.), in which the points of the mandibles cross each other. The 

 second and fourth of these forms are extremely rare ; they are exemplified, respectively, by 

 Skimmers and Crossbills (genera Rhynchops and Loxia). The first is common, occurring 

 throughout Birds of Prey and Parrots, and among Petrels, Gulls, etc. The great majority of 

 birds exhibit the third; and there is such evident gradation of paragnathism into epignathism, 

 that it is necessary to restrict the latter to cases of its complete development, exhibited in the 

 intermaxillary bone divested of its horny sheath, which often, as among Flycatchers, etc., 

 forms a little overhanging point, but does not constitute epignathism. These four classes, 

 though always determinable, and convenient in descriptions, are purely arbitrary — that is, 

 they by no means correspond to any four large groups of birds ; but, on the contrary, usually 

 only mark families and subdivisions of families ; and the four types may be seen in closely related 

 genera. The general shape of the bill has also furnished 



Other Classes, for many years used as a large basis for ornithological classification, even 

 for establishment of orders; but which progress of the science has shown to be merely as con- 

 venient as, and only less arbitrary than, the foregoing. The principal of these are represented 

 by the following types : A, among land birds. 1. Fissirostral (Lat. fissus, cleft, and rostrum), 

 or cleft, in which the bill is small, short, and with a very large gap running down the side of 

 the head ; as in the Swallow, Chimney-swift, Whippoorwill. 2. Tenuirostral (Lat. tenuis, 

 slender), or slender, in which the bill is slim, long, and with a short cleft ; as in the Humming- 

 bird, Creeper, Nuthatch. 3. Bentirostral (Lat. dens, a tooth), or toothed, in which, with a 

 various general shape, there is present a nick, tooth, or evident lobe in the apposed edges of 

 one or botli mandibles near the ena ; as in the Shrike, Vireo, and some Wrens, Thrushes, 

 Warblers. 4. Conirostral (Lat. conus, a cone), or conical, sufficiently defined by its name, 

 and illustrated by the Finch family and some allied ones. — B, among water birds. 5. Longi- 

 rostral (Lat. longus, long), or long, an aquatic style of the tenuirostral, best exhibited in the 

 Snipe fsimily. 6. Pressirostral (Lat. pressus, pressed), or compact, illustrated by Plovei's, 

 etc., and quite likely analogous to the conirostral. 7. Cultrirostral (Lat. citlter, a knife), cut- 

 ting, perhaps analogous to the dentirostral, exemplified by Herons. 8. Lamellirostral (Lat. 

 lamella, a little plate), or lamellate, in which the bill is furnished with series of little laminae 

 along the apposed edges of both mandibles, as in Swans, Geese, Ducks, Mergansers, Flamin- 

 goes, and certain Petrels. None of these terms is now used to indicate a natural group, nor 

 have we such absurdities as " orders " Fissirostres, Tenuirostres, etc. Swallows, for instance, 

 and Swifts are equally fissirostral, though only distantly related to each other; a Swift is 

 closely related to a Hummingbird, though the latter is extremely tenuirostral ; and birds of 

 contiguous genera may be dentirostral or not. The terms are nevertheless convenient to use 

 in descriptions. Some similar terms, expressing special modifications, as nnguirostral (Lat. 

 unguis, a hook), acutirostral (Lat. acutus, sharp), etc., are also employed. 



Other Forms. — A bill is called long, when notably longer than head proper; short, 

 when notably shorter ; medium, in neither of these conditi(ms. It is compressed, when higher 

 than wide, at base at least, and generally for some portion of its length ; depressed, when 

 wider than high ; terete (Lat. teres, cylindric), under neither of these conditions. It is recurved, 

 when curved upward; decurved, when curved downward; hent, when the variation in any 

 direction is at an angle, as in Flamingoes and the Wry-billed Plover ; straight, when not out 

 of line with axis of head. A bill is obtuse (said chiefly of the paragnathous sort) when it rap- 

 idly 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 slenderer; attenuate, when still 

 slenderer; subulate (awl-shaped), when slenderer still; acicular (needle-shaped), when slen- 

 derest possible, as in some Hummingbirds and Phalaropes. A bill is arched, vaulted, turgid, 



