No. I.] THE CRANIUM IN THE OWLS. 153 



eyes, and consequently their upper and lower ends (more par- 

 ticularly upon the right side) extend slightly past the highest 

 and lowest points in the eyeball. 



The distal border in either auricular opening is surrounded 

 by a thick and somewhat raised fold of integument similar 

 to what is found in the other species. The flaps are large 

 and somewhat asymmetrical, though in a less degree than in 

 5. aluco. The flap is larger on the right side, and has a 

 length that somewhat exceeds that of the ear-opening, being 

 about 35 mm. The width is 17 mm., and this flap is less 

 obliquely truncated than it is upon the left side ; its lower 

 end is, transversely, quite straight. The ear-flap is, upon the 

 left side, greatly narrowed above and broadest below, where it 

 forms a long, produced, and deflected extremity. The length 

 and breadth of this flap do not materially differ from the same 

 measurements given for the right side. 



Across either auricular opening there is stretched a fold of 

 skin or tensor muscle ^ that is attached at a point somewhat 

 above the middle of the lid ; on the right side this arises from 

 the tuberous and comparatively inferiorly situated superior 

 border of the osseous crest of the alisphenoid (or the large 

 orbital wing) ; on the left side this tubercle is found higher 

 up and less prominent, and the tensor muscle passes this, its 

 origin being found upon the posterior aspect of the osseous 

 crest of the squamosal bone, at its superior extremity. Owing 

 to the formation of the cranium, the entrance to the ear, or 

 the canal leading from the same to the parts within, has a 

 different direction upon the two sides. On the right side this 

 canal passes almost directly into the cranium immediately be- 

 neath the tensor muscle of the ear-flap ; on the left it passes 

 obliquely downwards beneath the muscle. 



The nostrils are comparatively large, elevated, somewhat 

 oblong; their longitudinal diameter is 7 mm., the height 5 mm. 



The cranium, which is asymmetrical, resembles in its struc- 



^ I presume Professor Collett means the "tensor muscle," the same having 

 the appearance of a " fold of skin." It reads in the original " Strcekker siq en Hud- 

 fold eller Lukkemuskel." To be sure, the muscle is included within a fold of 

 skin.— R. V^. S. 



