142 SHUFELDT. [Vol. XVII. 



process, which, when the cranium is viewed laterally, conceals 

 the distal extremity of the quadrate. Viewed from in front, 

 they are almost completely hidden behind the broad orbital 

 wings (that is, the osseous crests of the alisphenoids). 



The siipraoccipital {squajna occipitis) has a very minute and 

 circular supraoccipital foramen (diameter barely i mm.). The 

 pterygoid bones are, as in Nyctea, narrowed both before and 

 behind, and develop cultrate margins both superiorly and 

 inferiorly ; the articular facets for the palatines are triangular 

 in form. The palatines themselves are comparatively slender ; 

 the pars plajta, upon either side of the mesetJimoid, long and 

 stout, and extends far out beyond the external border of the 

 palatine bone, when we view the skull upon its basal aspect. 



Vomer rudimentary, and somewhat enlarged mesially. In- 

 feriorly, the niaxillo-palatines are separated but by a small 

 interval of space. 



5. Asio AcciPiTRiNUS (Pall.), 1 77 1. 



(Plate XV, Figs. 7 and 8. — Plate XVI, Figs. 9-1 1.) 

 Auricular openings and their flaps asymmetrical ; cranium symmetrical. 



The dermal parts of the auricular openings are asymmetrical, 

 remarkably long, being almost level with the top of the head, 

 and resemble gill-slits. They extend from the frontal region 

 in a curved direction {Jialvbue) down to the nether side of the 

 lower jaw, where they reach or even pass beyond the angle 

 of the gape (the superior angles of these slits are separated 

 at the vertex of the head by a very narrow interval). Their 

 vertical height in an adult specimen (collected at Krogskoven, 

 Oct. 16, 1876) is about 35 mm. 



The auricular opening, both in front and behind, is bounded 

 by a raised fold of skin, that extends the entire length of the 

 aperture, performing the function of the ear-flap, although the 

 true ear-flap is here, as well as in the other species possessing 

 it, composed of the anterior, which is at the same time the 

 larger fold of skin. This, the true ear-flap, is crescentic in out- 

 line (narrowing upwards and downwards), and broadest in the 

 middle (about 12 mm. wide). While, on the whole, this ear-flap 



