Cuass Il. PUFFIN AUK. 
are one inch and three quarters long; and the 
base of the upper mandible one inch broad; but 
in the birds from the Jsle of Zan these propor- 
tions are much less.* The nostrils are very long 
and narrow; commence at the above-mentioned 
rim, terminate at the first groove, and run pa- 
rallel with the lower edge of the bill. The irides 
are grey, and the edges of the eye-lids of a fine 
crimson; on the upper eye-lid is a singular cal- 
lous substance, grey, and of a triangular form; 
on the lower is another of an oblong form; the 
crown of the head, the whole upper part of the 
body, tail, and covert feathers of the wings, are 
black, but in some the feathers of the back are 
tinged with brown; the quil feathers are of a 
dusky hue. The cheeks are white, and so full 
of feathers as to make the head appear very 
large and almost round; the chin is of the same 
color, bounded on each side by a broad bed of 
grey; from the corner of each eye is a small 
separation of the feathers terminating at the back 
of the head. The neck is encircled with a broad 
* The form, and the color of the bill varies according to the 
age of the bird. ‘These changes are distinctly noticed in Mr. 
Pennant’s Tour in Wales, vol. iii. 40, and in the plate which 
accompanies it. The observations together with specimens of 
the bills of this, and the Auk, were communicated by the reves 
rend Hugh Davies. Ep. 
153 
