STRIGES: NOCTTJRNAL BIRDS OF PREY. 619 



toe not shorter than inner, and rarely versatile. Basal joint of middle toe longer than the next. 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. Feet sympelmous or desmopelmous : 



tendon of flexor perforans supplying 2d-lth toes, that of flexor hallucis going to 1st toe and by 



vinculum to 2d toe Fai,coxid.s; 



Outer toe reversible, and plumage without aftershafts. Feet sympelmous, but tendon of flexor per- 

 forans going to 2d-4th toes, that of flexor hallucis to all the toes PASDIONID.E 



Physiognomy peculiar by reason of great lateral expansion, lengthwise contraction and diploic thickening of 

 the often unsymmetrical cranium ; eyes looking forward, surrounded with a radiated disc of modified 

 feathers, in front appressed, autrorse, hiding base of bill. Nostrils usually at edge of the cere. Tomia 

 never lobed or toothed. A large external ear-conch often developed. Outer toe completely versatile, 

 shorter than iimer toe. Basal joint of middle toe not longer than second, much shorter than the penul- 

 timate one. Feet usua'ly feathery or bristly to or on the toes. Oil-gland nude. Plumage usually with- 

 out aftershafts, soft and lax ; flight noiseless. Ambiens absent. Feet desmopelmous, tendon of flexor 

 perforans to 2d^th toes, that of flexor hallucis to hind tee, only by vinculum acting also on 2d-4th toes. 



Nocturnal STRIGES 



Sternum entire behind, with central emargiuation : furculum anchylosed. Middle claw pectinate. 



Facial disc complete, triangul:ir ALCC0NiD.a; 



Sternum notched or fenestrate ; furculum free. Middle claw not pectinate. Facial disc circular 

 when complete Strioid.s; 



Suborder STRIGES : Nocturnal Birds of Prey ; Owls. 

 (Accipitres Nocturnes, or Nyctharpages.) 



Head very large, and especially bri)ad from side to side, but sliorteued lengthwise, the 

 "face" thus formed further defined by a more or le.^s 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 

 tlie nearest approach, among birds, to the ear-conch of mammals. Bill shaped much as in or- 

 dinary Accipjitres, but thickly beset at base with close-pressed antrorse bristly feathers, and 

 never toothed. Nostrils large, commonly opening at edge of cere rather than entirely in its 

 substance. Hallux of average length, never obviously elevated ; outer toe more or less perfectly 

 versatile (never permanently reversed), shorter than inner toe ; its first tliree 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 middle toe pectinate in some 

 species. As a rule, tarsi more or less completely feathered, and whole foot often thus covered. 

 Among numerous osteological characters may be mentioned frequent asymmetry of skull; wide 

 separation of inner and outer tablets of brain-case by intervention of spongy diploe ; spongy 

 maxillo-palatines an<l lacrymals, which latter long persist distinct ; desmognathous palate ; 

 holorhinal nostrils ; ba.'^i[)terygoid processes ; commonly mjinubriated and 4-notched (if not 

 entire) sternum ; a peculiar structure of tarso-metatarsus ; a particular arrangement of bones 

 about the shoulder-joint, and weakness of furculum when not anchylosed with sternum. The 

 cervical vertebrfe appear to be constantly 14. Five pairs of ribs reacli the sternum. Gullet 

 capacious, but not dilated into a special crop; gizzard only moderately muscular; intestines 

 short and wide; coeca extremely long, club-shaped, sometimes largely dilated at the ends. 

 Syrinx wholly bronchial, with one pair of intrinsic and one of extrinsic muscles. Oil-gland 

 nude or barely tufted. Ambiens absent, as also semitendinosus and accessory, accessory femo- 

 rocaudal, biccj)S slip, and expansor of secondaries ; feniorocaudal present. Feet desmopelmous, 

 in the peculiar way abovesaid. Wings aquintocubital. The featliers liave no aftcrsliaft, or 

 exceptionally a very small one, and the general plumage is very soft and lilended. 



The Nocturnal Birds of Prey will lie immediately recognized by tlnir peculiar pliysi<ig- 

 ni.iiiy, in.lepciKlcntly of tlie technical characters that mark tlu-m as a natural, sharply-defined 



