No. I.] 



THE CRANIUM IN THE OWLS. 



141 



The beak is somewhat long and strong, the mandibles, when 

 not covered by their horny theca, measured from the frontal 

 bones, will enter a little more than twice into the total length 

 of the cranium. The superior surface of the cranium exhibits 

 a median furrow, which, as in Nyctea, is deepest in the frontal 

 region at the mandibular base and between the parietals. 

 The orbits are markedly capacious, the diameter in each being 

 twice as long as the postorbital part of the cranium. The 

 crest of the alisphenoid (posterior orbital process) is conspicu- 

 ously broad and prominent above, and powerfully developed. 



Fig. 3- 



■ Left lateral view of skull of Bubo ignazms ; two-thirds natural size. 

 (Shufeldt, after CoUett.) 



The forehead is, as in Nyctea scandiaca, somewhat contracted 

 posterior to the supraorbital processes, and the latter are 

 situated comparatively far forwards (anterior to the middle 

 of the orbits). 



Th.Qf rentals, where they enter into the posterior peripheries 

 of the orbits, are sharp ; the thickening of the frontal region 

 in the vicinity of the supraorbital processes is especially well 

 marked. The thinner (transparent) part of the interorbital 

 septum is less extensive than it is in Nyctea scandiaca, from 

 the fact that the alisphenoid is thicker in front of the optic 

 foramen than it is in that species, which is likewise the case 

 with the mesethmoid element. The osseous crest of the ^j- 

 squamosum is, comparatively speaking, feebly developed, but, 

 upon the whole, somewhat stronger than it is in Nyctea; it 

 is, as in that genus, completely free superiorly, and develops 

 in the margin there a semi-anteriorly directed sharp-pointed 



