172 FALCONINiE. 



moderate size, varying from circular to linear, and opening near 

 the anterior margin of the cere. The aperture of the ear is 

 round or elliptical, and rather large. 



The legs are of moderate length or elongated ; the tibia very 

 muscular ; the tarsus sometimes feathered, generally bare, 

 usually scutellate in front and behind, sometimes scaly all 

 round. The toes are four ; the first large and stout, the third 

 longest, the second larger than the fourth ; the anterior some- 

 what webbed at the base ; all scutellate toward the end, some- 

 times in their whole length, padded and tuberculate or papillate 

 beneath. The claws are long, moderately compressed, tapering, 

 very acute, and with a great range of motion, although not re- 

 tractile, as usually alleged. 



The plumage is generally full ; the feathers compact on the 

 upper parts, those on the outer side of the tibia elongated ; but 

 great variations are observed in their form and texture. The 

 skin is entirely covered with soft down, which on the fore part 

 of the breast, on the sides under the wings, and on part of the 

 abdomen, is usually not intermixed with feathers, although 

 more or less covered by them. Individually the feathers are 

 very downy at the base, with a large plumule ; the tube is 

 short, but enlarged, the shaft slender. 



The wings are of great size, but vary in form, being very 

 long or of moderate length, pointed or rounded. The tail, 

 which is always of twelve feathers, is never small, but varies 

 extremely in length and form, being even, graduated, emargi- 

 nate, or forked. 



The cranium, PL I, is generally roundish, with the orbits ex- 

 tremely large, their septum with a vacuity in the centre ; the 

 nasal cavity rather large ; a distinct superciliary bone projecting 

 from the edge of the orbit ; the jaws short. The vertebras vary 

 in number, but are generally thus : twelve cervical, nine dorsal, 

 twelve sacral, eight caudal. The ribs, seven in number, are 

 rather stout ; the pelvis large. The sternum is usually of great 

 size, deeply convex, with a very prominent keel, the posterior 

 margin even, the coracoid bones very large and spreading, the 

 furcula very wide and of great strength ; the scapulae of mode- 

 rate size and slightly curved. The bones of the inferior extre- 



