No. I.] 



THE CRANIUM IN THE OWLS. 



151 



ing from the frontal bones, and not including the horny theca 

 that covers it. Upon the superior aspect of the cranium there 

 is a very distinct median furrow, which, in the three specimens 

 examined, is best marked at the cranial vertex in the inter- 

 parietal region. 



The orbital cavities are comparatively smaller than they are 

 in ^. ahico, inasmuch as the os alisphcnoides is here shorter and 

 thicker. Taken upon the whole, the orbital diameter is of 

 about the same length in the two species. The big orbital 

 wings (the osseous crests of the alisphenoids) are in both 

 these owls comparatively broad and large. The frontal region, 

 posterior to the supraorbital processes, is conspicuously wide, 

 and even much wider than it is in front of them, where it 

 gradually narrows anteriorly, but not in as marked a degree as 

 it does in vS. aluco. The frontal bone is, upon either side, 

 thoroughly rounded off where it forms the hinder border of 

 the orbit, but it is seen to slope obliquely away in the direc- 

 tion of the large orbital wing, so that we are enabled to see 

 the supraorbital processes 

 when the cranium is 

 viewed upon direct pos- 

 terior aspect. 



The intet'orbital septum 

 is quite thick transversely, 

 inasmuch as both os ali- 

 spJienoides and os eth- 

 moides enjoy a similar con- 

 dition throughout all their 

 parts ; as in Asio there is 

 only a localized area, situ- 

 ated above the rostrum of 

 the sphenoid, where the 

 septum is thin and semi- 

 transparent. The osseous 

 crest of the os sqtiamostim 

 agrees entirely with what was found in 5, aluco, being an out- 

 standing, nail-like, and superiorly free process ; but at the same 

 time it exhibits in the slight forward inclination of its anterior 



Fig. 4. — Cranium of Syrnhttn uralense, seen from above, 

 and showing slight asymmetry of the crests of the os 

 squatnosum ; compare this with same view of cranium of 

 .S". lappo7iicu7K. (Adapted by the author from Collett. ) 



