EXTEBNAL PARTS OF BIRDS. — THE BILL. 101 



Four Classes, representing as many "ways in whicli the two mandibles close upon each 

 other at the end. 1. The epignathous (Gr. iiri, epi, upon, yvddos, gnathos, jaw) way, plan, or 

 type, in which the upper mandible is longer than the under, and its tip is evidently bent down 

 over the tip of tlie lower. 2. The hypognathous (Gr. vtto, hupo, under), in which the lower 

 mandible is longer than the other. 3. The paragnathous (Gr. nupd, para, at or by), in which 

 both are of about equal length, and neither is evidently bent over the other. 4. The metugfia- 

 thous (Gr. fifTa, meta, with, beside, etc.), in which the points of the mandibles cross each 

 other. The second and fourth of these are extremely rare; they are exemplified, respectively, 

 by the skimmer and the cross-bill (genera Rhynchops and Loxia). The first is common, 

 occurring throughout the birds of prey, the parrots, and among the petrels, gulls, etc., etc. 

 The great majority of birds exhibit the third ; and, among them, there is such evident grada- 

 tion into epignathism, that it is necessary to restrict the latter to its complete development, 

 exhibited in the intermaxillary bone divested of its horny sheath, which often, as among fly- 

 catchers, etc., forms a little overhanging point, but does not constitute epignathism. These 

 classes, it should be added, though always applicable, and very convenient in descriptions, are 

 purely ai-bitrary, that is, they by no means correspond to any four large groups of birds ; but, 

 on the contrary, usually only mark families and the subdivisions of families ; and the four 

 types may be seen in contiguous 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 the establishment of orders ; but which the progress of the science has shown to be merely 

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

 represented by the following types : A, among land birds. 1. The fissirostral (Lat. fissus, 

 cleft, and rostrum')^ or cleft, in which the bill is small, short, and with a very large gap run- 

 ning down the side of the head ; as in the swallow, chimney-swift, whippoom^ill. 2. The 

 tenuirostral (Lat. tenuis, slender), or slender, in which the bill is small, long, and with a short 

 cleft ; as in the humming-bird, creeper, nuthatch. 3. The dentirostral (Lat. dens, a tooth), 

 or toothed, in which, with a various general shape, there is present a nick, tooth, or evident 

 lobe in the opposed edges of one or both mandibles near the end ; as in the shrike, vireo, and 

 some WTcns, thrushes, and warblers. 4. The conirostral (Lat. conus, a cone), or conical, suflft- 

 ciently defined by its name, and illustrated by the great finch family and some allied ones. — 

 B, among water birds. 5. The longirostral (Lat. longus, long), or long, an aquatic style of 

 the tenuirostral, best exhibited in the great snipe family. 6. The i)ressirostral (Lat. pressus, 

 pressed), or the compact, illustrated by the plovers, etc., and quite likely analogous to the 

 conirostral. 7. The cultrirostral (Lat. culter, a knife), cutting, perhaps analogous to the 

 dentirostral, exemplified in the heron group. None of these terms are now used to indicate 

 natural groups, nor have we such absurdities as the " orders " Fissirostres, Tenuirostres, etc. 

 A swallow, for instance, and a swift are equally fissirostral, though only distantly related to 

 each other ; a swift is very closely related to a humming-bird, though the latter is extremely 

 tenuirostral ; and birds of contiguous genera may be dentirostral or not. The words are 

 nevertheless convenient incidental terms in general descriptions. Various other similar terms, 

 expressing special modifications, as lamellirostral (Lat. lamella, a plate), acutirostral (Lat. 

 acutus, sharp), etc., are also employed as common names, simply descriptive of 



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

 when notably shorter ; medium, in neither t)f these conditions. 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 (Lat. teres, cylindric), under neither of these conditions. It is recurved, 

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

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



