ALCID^ — PHALEBIDIN^ : 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, in 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 long, naiTOw, 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 two pairs of lateral pieces ; in all, 
9 or 7 pieces (9 in arctica and glacialis, 7 in 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 acute, below by a horizontal, lengthened, 
callosity. No crests on head, but a furrow in plumage behind eye. Wings not peculiar. 
Tail rounded, but central feathers shorter than the next, contained about 2i times in length 
of wing, 16-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, upright ; middle claw dilated on inner edge ; inner claw enlarged, curved to a semi- 
circle, very acute, usually lying horizontal. Sexes ahke ; 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 burrows 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 glacialis 855 
853, F. cornicula'ta. (Lat. corniculata, having a little horn (over the eye). Fig. 534.) Horned 
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 fur 
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 of a circle ; tip of upper 
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 otherwise 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 narrow 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 with 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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