A binary division of the class may be found ed on the condition of the newly-hatched young, which in some orders are able to run about and provide food for themselves the mo ment they quit the shell (_4ves precoces) ; while in others the young are excluded feeble, naked, and blind, and dependent on their pa rents for support (Ayes altrices).
ScoPoLI, in his Introduction to Natural History,' published in 1777, proposed a dicho tomous systematic distribution of Birds, found ed on the form of the scales covering the tarsus. The species which have these scales small and polygonal are the Retepedes of this author; those which have the legs covered anteriorly with unequal semicircular plates are the Scutipedes.
Nitzsen," the celebrated professor of natural history at Halle, has synthetically grouped to gether the feathered tribes under three grand orders, according to the great divisions of the terraqueous globe which form the principal theatres of their actions.t The first order con sists of the birds of the air par excellence, Ayes aereee (Luft-vogeln); the second order em braces the birds of the earth, Ayes terrestres (Erd-vogeln) ; the third great division includes the birds which frequent the waters, Ayes aqua ticee (Wasser-vogeln). The Eagle and the Sparrow may be named as examples of the first ; the Ostrich and the common fowl of the second ; the Heron and the Gull of the third of these extensive divisions.
A more definite arrangement of Birds, in which a similar principle may be traced, has been proposed by a distinguished naturalist of our own country, Mr. Vico as. lie divides the class Ayes into five orders. The first includes the birds which soar in the upper regions of the air, which build their nests and rear their young on the highest rocks and loftiest trees, and which may be regarded as the typical species of Nitzsch's Aerial Birds ; this order is termed Raptores, from the rapacious habits and animal food of the species so grouped to gether.
The second order affects the lower regions of the air ; the birds composing it are peculiarly arboreal in their habits, and are therefore term ed Perchers or Insessores.
The third order corresponds to Nitzsch's Ayes terrestres, and is denominated Rasores, from the general habit which these granivorous species present of scratching up the soil to obtain their food.
By dividing the aquatic birds of Nitzsch into those which frequent the fresh waters, and are limited to wading into rivers, lakes, &c. in search of their food, and those which possess the power of swimming in the great ocean, we ob tain the two remaining orders of the arrangement of Mr. Vigors, viz. the Grallatores, or Waders, and the Natatores, or Swimmers. The merit of this system is not, however, confined to the defining of the different groups in as clear and readily appreciable a manner as the subject will admit; but it also aims at displaying the natural affinities by which the several orders and families are connected with and pass into one another. In the ornitholo gical systems of other naturalists, who have made this branch of zoology their particular study, we find the greatest discrepancy both as to the number and value of the primary divi sions of the class.
Sandewall has, four orders or cohorts.
Vieillot, like \Tigors has five orders. Linnoeus, Cuvier, dams, and Dumeril have six orders.
Illiger has seven.
Scopoli, Latham, Meyer, Wolf and Blain ville have nine.
Temminck (1820) has sixteen.
Schaeffer has seventeen.
Brisson has twenty-eight, and Lacepede has thirty-eight orders.
Where so many masters of the science differ, it is difficult for one less profoundly versed in ornithology to select the most unexceptionable system of arrangement, and as ob serves, the choice perplexes.' We have here adopted the arrangement proposed by that dis tinguished naturalist as being the one which facilitates the expression of the leading ana tomical differences which obtain in the class of Birds, and which may therefore be considered as the most natural.
Order I. RAPTORES.
Body, very muscular.
Beak, strong, cur ved, sharp-edged and sharp-pointed, often armed with a lateral tooth ; upper man dible the longest. ( Fig 112.) Legs, robust, short, with three toes before, and one behind ; all armed with long, strong, crooked talons. Fig.113.