COMMON RAZOR-BILL. 347 



the other parts nearly as in summet\ Yoimg at first coloured 

 like the adult in summer, afterwards like the adult in winter, 

 but altvays distinguishable by having the bill smaller, much 

 less elevated, without grooves, and black. 



Male in Winter. — The Razor-billed Avik, which closely 

 resembles the Slender-billed Guillemot in form and colour, is 

 somewhat less than that species, and distinguished from it by 

 its much deeper compressed bill, somewhat resembling the 

 blade of a knife. The body is rather elongated, full, and 

 somewhat depressed ; the neck short and thick ; the head 

 large, ovato-oblong, anteriorly narrowed. The bill is shorter 

 than the head, very high, much compressed ; the upper man- 

 dible with its lateral or nasal sinuses extremely large, extend- 

 ing to more than half its length, leaving only a narrow mar- 

 gin below, forming an angle before, and covered with feathers, 

 its upper margin oblique, forming a narrow ridge, the outline 

 of the horny part arcuato-decurvate in the third of a circle, 

 the ridge very narrow but convex, the sides nearly flat and 

 erect, with five transverse curved grooves, of which that next 

 the basal rim is deepest, the edges inflected and sharp, the 

 tip decurved and narrow, but blunt ; the lower mandible 

 with the intercrural space long and very narrow, the crura 

 for half their length covered with feathers, leaving only a 

 very narrow horny margin, but ultimately enlarged, the dorsal 

 line ascending and slightly concave, the sides nearly flat, with 

 four transverse shallow grooves, the edges sharp and inflected, 

 the tip somewhat decurved, the gape-line straight, at the end 

 decurved. 



The mouth is of moderate width, opening far before the 

 eyes ; the palate with two papillate ridges, and several series 

 of reversed papillse ; its anterior part with five prominent 

 lines. The tongue, an inch and a quarter in length, is slen- 

 der, fleshy, flat above, with a medial gi-oove, and tapers to a 

 thin horny point. The oesophagus, eight inches long, is 

 about an inch in width, but on entering the thorax enlarges 

 to an inch and three fourths, forming an enormous proventri- 

 cular sac, the greater part of Avhich is occupied by the very 

 numerous glandules. The stomach is small, elliptical, ten- 



