.160 PTERYLOGRAPHY OF GOAT-SUCKERS AND OWLS— CLARK, vol.xvii. 



triple row of small feathers ou the lower edge of the patagiiiin, while all 

 of the upi^er outer corner of the breast is usually more or less feathered. 

 From the lower end of the sternal tract there runs a strong hook over 

 to the hypopterum, which is itself very evident. There are two rows of 

 primary and three or four of secondary under coverts. The ventral tracts 

 commence on the breast, usually near the furcula, and seem to be fused 

 with the sternals at first, but soon separate from them and run down on 

 either side almost to the anus, becoming very narrow on the belly. 

 Strix shows a very peculiar modification of this typical form, in the 

 fusion again of the sternal and ventral tracts at the posterior end of 

 the former. The jiost-anal tract, comj^rising the under-tail coverts, is 

 strong and very conspicuous in the larger species. All of the speci- 

 mens of Striges examined agreed in the following details: 



Aftershafts wanting. True down wanting. Oil gland not tufted. 

 Primaries 11, the eleventh very small. Eectrices 12 (except Micropallas), 

 Alula feathers 4. Wing aquiucubital. 



As only nine species, representing eight genera, have been available 

 for study they can not be very satisfactorily arranged in groups ptery- 

 lographically, but when all the genera are examined such an arrange- 

 ment may be possible. For the sake of convenience I have, however, 

 divided the eight genera as follows: 



I. Head uuiformly and thickly feathered above aud sometimes below, altbougli the 



lateral neck spaces reacli nearly to the ears and the infra-maudibular 

 region is sometimes sjjarsely feathered, often showing apteria along 

 the rami of the lower jaw. 



A. Eectrices 10 Micropallas. 



B. Eectrices 12. 



a. Upper cervical tract well forked ; ninth, eighth, and seventh primaries 

 longest Spkotyto. 



h. Upper cervical tract slightly forked ; seventh, sixth, and eighth primaries 

 longest Glaucidium. 



II. Head not uniformly feathered, but usually showing longitudinal rows on the 



crown, and the infra-mandibular region is very sparsely feathered. 



A. Sternal tract free from ventral at posterior end ; outer pair of rectrices shortest. 



a. Linear arrangement of feathers near the center of the crown between the 



eyes, but on account of their nearness to each other not showing 

 any very definite pattern; lower cervical tract clearly defined on the 

 chin Sybnium. 



b. Linear arrangement of feathers on the crown forming a definite pattern 



between the eyes or else not evident at all ; lower cervical tract 

 indistinct on the chin ; ninth, eighth, and seventh primaries longest. 



Asio. 

 0. Linear arrangement of feathers on the sides of the crown, back of the eyes. 



1. Tarsus fully feathered; seventh, sixth, and eighth primaries longest. 



Megascops. 



2. Tarsus only feathered in front halfway to the toes Gymxoglaux 



B. Sternal tract fused with ventral behind as well as in front; middle pair of 



rectrices shortest. 



a. Ninth, eighth, aud tenth primar.es longest Strix. 



Note. — The above .arrangement is not intended to show any affinities between 

 these genera, but simply to set out more iirominently some of the differences. 



