2 U. S&S. P. R R. EXP. AND SURVEYS——-ZOOLOGY—GENERAL REPORT. 
characters of many of the subdivisions for myself. In the discussion of the higher groups I 
have however derived invaluable assistance from the work of Burmeister. I have also made 
constant use of the diagnoses of Keyserling and Blasius, which are pre-eminent for acuteness 
and precision. 
The following synopsis of the orders of birds, taken partly from Keyserling and Blasius, 
will serve to illustrate the characteristics of the higher groups in American Ornithology. 
A.—HIND TOE ON THE SAME LEVEL WITH THE ANTERIOR ONES. 
a.—Posterior face or the sides of the tarsus more or less reticulated, granulated, or with 
scales more numerous or smaller than in front; sometimes naked. Anterior face of the tarsus 
never in one unbroken plate. Larynx without complex vocal muscles. 
Order I.—Raptores. Base of the upper mandible with a soft skin or cere. Upper man- 
dible compressed ; its point curving down over that of the lower, forming a strong, 
sharp hook. Claws generally retractile. Toes never two behind. Birds usually of 
large size, and of powerful frame, embracing the so-called birds of prey. 
Order I1.—Scansores. Toes in pairs; two in front and two behind, the outer anterior 
being usually directed backwards, (the inner in Zrogonidae.) Tail feathers eight to 
twelve, 
Order III.—Srrisores. Toes either three anterior and one behind, (or lateral) or four 
anterior ; the hinder one is, however, usually versatile, or capable of direction more or 
less laterally forward. ‘Tail feathers never more than ten. Primaries always ten, the 
first long. 
Order [V.—Cramarores. Toes, three anterior and one posterior, (not versatile.) Pri- 
maries always ten, the first nearly as long as the second. Tail feathers usually 
twelve. 
6.—Anterior face of the tarsus in one continuous plate, or divided transversely into large 
quadrate scales. Plates on either the posterior serface of the tarsus or the sides, without sub- 
divisions, never both divided together ; when divided the divisions correspond with the anterior 
ones. Larynx with peculiar complex singing muscles. 
Order V.—Oscines. Toes, three anterior, one posterior. Primaries either nine only, or 
if ten the first usually short or spurious. 
B.—HIND TOE RAISED ABOVE THE LEVEL OF THE REST. 
Order VI.—Rasorzs. Nostrils arched over by an incumbent thick, fleshy valve. Bill 
not longer than the head, obtuse anteriorly. Nails broad, obtusely rounded. 
Order VII.—Gratiatores. Legs lengthened, adapted for walking, naked above the knee. 
Nostrils naked. Thighs usually quite free from the body. Toes not connected by a 
membrane, or for a short distance only; sometimes with a lobed margin. 
Order VIII.—Nartatorzs. Adapted for swimming. Legs generally short. Toes united 
by a continuous membrane. Thighs mostly buried in the muscles of the body. 
Fuller explanations of the characters of these orders will be found under their proper heads 
in the following pages. 
