BIRDS OF NORTH AND MIDDLE AMERICA. 505 



absent; clavicle weak and nearly cylindrical, about equal in length 

 to sternum; praecoracoid processes produced forward to meet the 

 clavicle, beneath basal process of scapula; cctepicondyloid process 

 of humerus small; ramphotheca simple, raptorial, with ceroma; 

 tibia more than twice as long as tarsus, without bony ridge for exten- 

 sor tendons; hallux more than half as long as fourth toe and on a 

 level with anterior toes; fourth (outer) toe freely reversible, shorter 

 than second (inner) toe ; basal phalanx of middle toe not longer than 

 second phalanx and much shorter than third ; basal phalanx of sec- 

 ond (inner) toe much abbreviated; ambiens, accessory femorocau- 

 dal, semitendinosus, and extensor secundariorum muscles and biceps 

 slip absent ; flexor tendons of type I, the flexor longus hallucis leading 

 to the hallux, the flexor perforans digitorum leading to the second, 

 third, and fourth toes; oesophagus destitute of dUated crop; caeca 

 large, unusually long, club-shaped; syrinx bronchial, with one pair 

 of muscles ; intestinal convolutions of type VI ; gall-bladder present 

 (except in genus Speotyto); oil-gland nude; spinal pteryla well 

 defined on neck, forked between shoulders; aftershaft absent in 

 Bubonidae, rudimentary in Tytonidae; adult downs wanting or 

 present on apteria only; primaries 11, but the eleventh (outermost) 

 one rudimentary; secondaries 11-18, rectrices 12 (only 10 in genus 

 MicroiMllas, occasionally 13 in Speotyto). 



General external characters of the Striges may be described as 

 follows : Eyes directed forward and surrounded by a radiating system 

 of feathers which is bounded, except anteriorly, by a line or run 

 of small, narrow, stiff, compactly webbed, differently formed, and 

 somewhat recurved feathers ("facial rim" or "border") ; loral feathers 

 antrorse, long, and dense, with bristle-like tips, covering base of bill 

 and usually hiding nostrUs ; plumage in general very soft and lax, of 

 fine downy texture; outer webs of primaries, especially the outer 

 one, with tips of the barbs recurved ; feathers on sides of forehead 

 or crown frequently elongated into ear-like or horn-lil^e tufts; tarsus 

 usually and toes frequently feathered, the feathering (when present) 

 soft and dense (that on toes sometimes sparse and bristle-like) ; bill 

 raptorial, but maxillary tomium never toothed nor notched; feet 

 raptorial, but outer toe freely reversible. 



Pterylographic characters of the Striges are thus described in detail 

 by !Mr. Hubert Lyman Clark : "• 



"The head is more or less fully feathered above, and especiaUy 

 densely in front. The upper cervical tract usually commences broad, 

 but rapidly becomes narrow, and forks between the shoulders more 

 or less deeply. The dorsal tract is very incomplete anteriorly and is 

 only indistinctly connected with the cervical forks, but posteriorly it 



a Proc. U. S. Nat. Mus., xvii, no. 1018, 1895, 559, 566. 



