No. I.] 



THE CRANIUM IN THE OWLS. 



139 



Fig. I. — Left lateral view of the skull of Nyctea scandiaca 

 (Linn.) ; two-thirds natural size. 



cranium has a longitudinal median furrow, which is especially 

 well marked in the region of the base of the superior mandible, 

 and between the parietal bones. 



The supraorbital processes are situated comparatively far 

 forwards (anterior to the middle of the orbits). 



The forehead, posterior to the supraorbital processes, is 

 somewhat contracted, narrower in fact than it is anterior to 

 these apophyses, and 

 the orbital borders 

 are here about par- 

 allel to each other. 

 The frontal bones are 

 sharp where they 

 form the posterior 

 borders of the orbits ; 

 the forehead is espe- 

 cially thick in the 

 region of the supra- 

 orbital processes. 



The thinner, semi- 

 transparent part of 

 the interorbital sep- 

 tum is extensive ; in 

 the middle of either 

 alisphenoidth.QrQ. is an 

 unossified area, and 

 in the cranium of one 

 of the specimens at 

 hand there are, more 

 anteriorly, in the direction of the ethmoid two other minute 

 areas of a similar character. 



The osseous crest of the squamosal bone is, comparatively 

 speaking, more feebly developed than it is in the other groups. 

 Superiorly, it terminates in a pointed process, that is directed 

 somewhat anteriorly, which, when the cranium is viewed upon 

 its lateral aspect, conceals from view the distal end of the os 

 quadratum. 



The broad orbital wings (that is, the osseous crests of the 



Fig. 2. — Left lateral view of the plucked head of a specimen 

 of Nyctea scandiaca (Linn.) ; two-thirds natural size. (Both 

 figures by Shufeldt, after CoUett.) 



