498 SYSTEMATIC SYNOPSIS. — RAPTORES— STRIGES. 
Physiognomy not peculiar; no great lateral expansion of the cranium or thickening of its walls 
with diploé; eyes looking sideways; no facial disc or only an imperfect one; base of bill not 
hidden by appressed feathers. Nostrils wholly in the cere. Tomia usually toothed or lobed. 
No external ear-conch. Outer toe not shorter than inner, and rarely versatile. Basal joint of 
middle toe longer than thenext. Feet with rare exceptions mostly or entirely naked of feathers, 
scutellate or reticulate, or both; toes always bare and scaly. Sternum commonly single- 
notched or -fenestrate on each side, sometimes entire. Oil-gland tufted. Plumage compact, 
usually aftershafted; flight audible. Ambiens present. Diurnal » . . ACCIPITRES. 
Outer toe not reversible, and plumage usually aftershafted . . FALCONIDA, 
Outer toe reversible, and plumage without aftershafts ® it as PANDIONIDZ. 
Physiognomy peculiar by reason of great lateral expansion, lengthwise contraction and diploic 
thickening of the often unsymmetrical cranium; eyes looking forward, surrounded with aradi- 
ated disc of modified feathers, in front appressed, antrorse, hiding base of bill. Nostrils usually 
at edge of the cere. Tomia never lobed or toothed. A large external ear-conch often devel- 
oped. Outer toe completely versatile, shorter than inner toe. Basal joint of middle toe not 
longer than second, much shorter than the penultimate one. Feet usually feathery or bristly 
to or on thetoes. Oil-gland nude. Plumage without aftershafts, soft and lax; flight noiseless. 
Ambiens absent. Nocturnal . . : . . . . STRIGES. 
Sternum entire behind, with central eniareinntions farculum anichylosed. Middle claw 
pectinate. Facial disc complete, triangular x + . + . ALUCONIDA. 
Sternum double-notched or fenestrate; furculum free. Middle daw not pectinate. Facial 
disc circular when complete ........4.. See. Ca . STRIGIDZ. 
6. SusorpeR STRIGES: Nocturna Birps oF Prey. 
Head very large, and especially broad from side to side, but shortened lengthwise, the 
“face” thus formed further defined by a more or less complete “‘ ruff,” or circlet of radiating 
feathers of peculiar texture, on each side. Eyes very large, looking more or less directly for- 
ward, set in a circlet of radiating bristly feathers, and overarched -by a superciliary shield. 
External ears extremely large, often provided with an operculum or movable flap, presenting 
the nearest approach, among birds, to the ear-conch of mammals. Bill shaped much as in 
ordinary Accipitres, but thickly beset at base with close-pressed antrorse bristly feathers, 
and never toothed. Nostrils large, commonly opening at the edge of the cere rather than 
entirely in its substance. Hallux of average length, not obviously elevated in any case; outer 
toe more or less perfectly versatile (but never permanently reversed), and shorter than the 
inner toe; its first three joints very short, altogether not as long as the succeeding one; basal 
joint of middle toe not longer than the next. Claws all very long, much curved and extremely 
sharp, that of the middle toe pectinate in some species. As a rule, the tarsi are more or less 
completely feathered, and the whole foot is often thus covered. Among numerous osteological 
characters may be mentioned the frequent want of symmetry of the skull, wide separation of the 
inner and outer tablets of the brain-case by intervention of spongy diploé, the spongy maxillo- 
palatines and lacrymals, which latter long persist distinct; the basipterygoid processes; the 
manubriated and commonly 4-notched (if not entire) sternum ; a peculiar structure of the tarso- 
metatarsus; a particular arrangement of the bones about the shoulder-joint, and the weakness 
of the furculum when not anchylosed with the stemum. The gullet is capacious but not 
dilated into a special crop; the gizzard is only moderately muscular; the intestines are short 
and wide; the cceca are extremely long and club-shaped. The syrinx has one pair of intrinsic 
muscles. The oil-gland is nude. The ambiens is absent. The feathers have no aftershaft, 
and the general plumage is very soft and blended. 
The Nocturnal Birds of Prey will be immediately recognized by their peculiar physiognomy, 
independently of the technical characters that mark them as a natural, sharply-defined group. 
They are highly monomorphic, without extremes of aberrant form; but the ease with which 
they are collectively defined is a measure of the difficulty of their rigid subdivision, which is 
not yet satisfactorily determined. Too much stress has been laid upon the trivial, although 
evident, circumstance of presence or absence of the peculiar ‘‘ horns” that many species possess. 
