No. I.] THE CRANIUM IN THE OWLS. 123 



vertical height of the cranium is posterior to the orbits. Vomer rudimen- 

 tary. Infraoccipital foramen present, and large in the case of G. pas- 

 serinum. The supraorbital processes in S. funerea long and styliform. 

 Crania lack the superficial median furrow upon their superior aspects. 



b. Jugal linear. 



3. Nyctea SCANDIACA (Linn.). 



Auricular openings of medium size and placed inferiorly. Osseous crest 

 of OS squamosufn comparatively small, and non-united superiorly ; viewing 

 the skull from in front, they are almost entirely concealed by the orbits. 

 Vomer rudimentary. Supraoccipital foramen present. Median furrow on 

 superior aspect of cranium present. 



To this first group, then, which includes species without 

 dermal ear-flaps, and where no asymmetry is present in any 

 part of the head, belong Surnia funerea, Glaucidiiim passeri- 

 miniy and Nyctea scandiaca. 



Of these three, the two first-named species constitute a 

 subgroup of themselves, since in certain of their cranial char- 

 acters which they exhibit in common and in which they differ 

 from the Norwegian species, they must doubtless be con- 

 sidered, systematically speaking, as allied to each other. Both 

 Surnia funerea and Glaiicidiwn passerimmi develop, superiorly, 

 upon the jugal bone an elevated, oblong process of some 

 length, while this bone in all the remaining North-European 

 species is linear. Further, the superior aspect of the skull is 

 flat and entirely lacking in a median furrow, which latter in 

 all the other species is present. Within this group the crania 

 can be distinguished in the two species one from the other, in 

 addition to the difference in size, by the feebler development 

 of the mandibles in Glaucidium passerinum, which in its case, 

 as compared with the cranium proper, are shorter than are the 

 mandibles in any other species. Further, the supraoccipital 

 foramen in this species is unusually large, both relatively and 

 absolutely ; in fact, larger than it is in any other form. In 

 addition thereto, Surnia funerea has the supraorbital processes 

 long and spiculiform, approaching in this respect the diurnal 

 Raptores. 



Nyctea scandiaca, constituting the second subgroup, has 



