OF EASTERN PENNSYLVANIA. Ki:i 



cious character, with thickly-set, antrorse, bristly feathers at 

 base. Nostrils large, but opening on the margin of the cere. 

 Hallux of the average length, but slightly elevated ; external 

 toes more or less versatile, and shorter than the internal toes ; 

 middle toe considerably pectinate in some species ; tarsi, as a 

 rule, more or less feathered ; claws long, much curved and 

 verv sharp. 



Other characters, which more clearly define this family, 

 are the separation of the inner and outer tablets of brain-case 

 by intermediate light spongy diploe ; the existence of four 

 notches in sternum, and the tarso-metatarsal structure. 



The gullet is large, but not expanded into a special crop ; 

 giz/ard moderately muscular ; intestines, short and wide ; 

 c<rca quite long and claviform. The syrinx has one pair of 

 internal muscles. Feathers devoid of aftershaft. and general 

 plumage, remarkably soft and blended. 



These Nocturnal Birds of Prey are easily recognized by 

 their rather peculiar physiognomy, independently of their 

 structural details. They are a highly monomorphic group. 

 The di Here nt subfamilies are not yet satisfactorily defined, too 

 much stress being placed upon the ear-tufts, rather than 

 upon more reliable characters. 



These birds are pre-eminently nocturnal ; but many striking 

 exceptions exist; the general habits of which are modified 

 by the size and structure of the eyes, which, in the typical 

 owls, arc best adapted to the subdued light of the evening, 

 or to the darkness of the night, rather than to the glare of 

 sunlight. Most species hide during the day in hollow trees, 

 dense foliage, or other gloomy retreats. Their flight is 

 noiseless, owing to the soft and somewhat downy texture ot 

 their feathers. Some feed entirely upon small quadrupeds, 

 birds, reptiles, and insects, which they capture alive ; while 

 others have been known, particularly in confinement, to sub- 

 sist upon dead animal matter. The bones, feathers, and 

 other indigestible substances, are ejected from the mouth in 

 round pellets. Their cries are loud and doleful. They 



