ALCIB^ — FHALEBIBINM : PUFFINS. 801 



space, or nasal fossa, its short base horizontal, its long sides rising and sloping backward 

 to meet at an acute angle at base of culmen ; the linear nostrils horizontal, close to com- 

 missure at base of this space, which in winter is naked and membranous, iu summer covered 

 with a symmetrical horny "saddle" sheathing the nasal fossa; with a basal raised "collar" 

 surrounding base of upper mandible, through numerous perforations of which protrude rudi- 

 mentary feathers ; with a small narrow horizontal horny strip on each side below nostrils ; 

 with usually, also, a Umg, narrow, obliquely vertical strip bounding the triangular space 

 anterior. Basal portion of under mandible contracted and membranous in winter, in summer 

 with a symmetrical horny " shoe '' which carries the line of the gonys downward and backward 

 to a point, and a narrow horny strip along base. These deciduous elements thus forming 

 three symmetrical pieces, surrounding the bill, and three or twii pairs of lateral pieces ; in all, 

 9 or 7 pieces (9 in arctica and glacialis, 1 iu corniculata) which are regularly moulted. 

 Angle of mouth with a rosette of naked skin, festooned in summer, shrunken in winter. 

 Eyelids surmounted above by a triangular, obtuse or iicute, below Ijy a horizontal, lengthened, 

 callosity. No crests on head, but a fuiTow in plumage behind eye. Wings not peculiar. 

 Tail rounded, but central feathers shorter than the next, contained about 23,- times iii length 

 of wing, 10-feathered. Tarsus very short, only equal to inner toe without claw, stout, little 

 compressed, reticulate except for a small space in front, which is scutellate. Outer toe about 

 equal to the middle ; its claw shorter than the middle claw, both slightly curved, not very 

 acute, ujiright ; middle claw dilated on inner edge ; inner claw enlarged, curved to a semi- 

 circle, very acute, usually lying horizontal. Sexes alike ; seasonal changes of plumage slight, 

 those connected with the moult of the bill very great. Egg single, white or scarcely marked, 

 laid in rocky crevices or buiTows in ground. 



Analysis of Species. 



Excrescence of upper eyelid forming a slender acute horn. Height of bill much greater than length of 



commissure. Black of throat reaching bill corniculata 853 



Excrescence of upper eyelid forming an obtuse process. Black of throat not reaching bill. 



Culmen moderately convex, its chord about 2.00; its arc 2.10; bill under 1.50 deep at base. Wing 



under 7.00 arctica 854 



Culmen very convex, its chord about 2.40 ; its arc 2.60 ; bill over 1.50 deep at base Wing 7.00 or 

 more glaclalis 855 



853. F. corniciila'ta. (Lat. corTOCJtfefo, having a little horn (over the eye). Fig. 534.) HoesteD' 

 Masking Puffin. Adult in summer : Appendage of the upper eyelid produced into a long, 

 slender, acute, upright horn ; that of lower eyelid linear-obtuse, horizontal. Bill very large, 

 especially high for its length, its height about equal to chord of culmen exclusive of the basal 

 collar, much greater than length of gape ; base of culmen and point of gonys both produced foi 

 backward, giving a very convex outline of feathers alongside the bill ; sides of bill not 

 distinctly divided into nasal compartment and grooved portion, nearly smooth, with only 

 three short shallow grooves ; culmen very convex, almost the sextant f)f a circle ; tip of uppef 

 mandible much hooked; rictus short, that portion in advance of the basal rim of upper man- 

 dible only about as long as upper mandible is deep ; outline of gonys sinuate, at first convex, 

 then more ascending, with slight concavity ; chord of gonys nearly as long as that of upper 

 mandible, exclusive of the basal rim or collar. Form othermse not peculiar in the genus. 

 Crown of head grayish-black, narrowing to a point at base of culmen. Sides of head white ; 

 the postocular furrow and sides of lower jaw ashy. A distinct naiTow line of white along 

 edge of fore-arm. Entire upper parts glossy blue-black ; a sootier shade of black encircling 

 the fore-neck, running forward on throat to bill. Other under parts white, except a few 

 elongated blackish feathers on sides of flanks. Lining of wings pearly-ash. Bill entirely 

 vermilion-red, even the basal collar ; edges of eyelids red ; excrescences of eyelids bluish- 

 gray ; iris brown ; feet orange-red, the webs tinged vdth vermilion ; claws brownish-black ; 

 rosette of mouth bright yellow-orange. Length 14.50; extent 24.50; wing 7-25 ; tail 2.75; 



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