20 PEOCEEDINGS OF THE ACADEMY OF 



Spheniscus, Moehring, Av. Gen. 1752. Not of authors. 



Fratercula, Brisson, Oniith, 17G0 ; and of many authors. 



Lunda, Pallas, Zoog. R-A. 1811 ; in part. 



Mormon, Illiger, Prodromus, 1811 ; and of most authors. Type Alcct 



arctica L. 

 Larva, Vieillot, Analyse, 1816. (Type Alca arctica L. fide Gray). 

 Ceratoblepharum, Brandt, Bull. Acad. Imper. St. Petersb. ii. 1837, p. 348. Type 

 Alca arctica L. 

 Bill rather longer than the head, or than the middle toe and claw, nearly as 

 high at the base as long, exceedingly compressed, the sides nearly vertical, the 

 base of the upper mandible with an elevated horny ridge, entirely surrounding 

 it ; the basal moiety of the upper mandible with its sides perfectly smooth, 

 forming an elongated oblique triangle with two curved sides ; terminal moiety 

 with three or four deep very oblique curved grooves, from commissure to 

 cuhnen, their convexity looking forwards. Under mandible without a basal 

 ridge, the basal moiety smooth, the terminal with grooves, in continuation of 

 those of the upper mandible. Culmen commencing on a level with the fore- 

 head, thence regularly decliiiate, very convex, with unbroken curve, its ridge 

 sharp, the tip acutely pointed, overhanging. Rictus perfectly straight, except 

 at the end ; the angle of the mouth occupied by a circular callosity of mem- 

 branous tissue; gonys ascending, slightly sinuate, the keel sharp, terminating 

 posteriorly in a thin, elongated, almost hamular process. Nostrils placed just 

 over the commissure, linear, long, reaching nearly across the base of the 

 smooth triangular space of the upper mandible. No nasal fossaj ; both eyelids 

 furnished with prominent callosities, in one species developing into a slender 

 acute process. No crest ; a peculiar furrow in the plumage behind the eyes, 

 as in Lomvia. Wings of ordinary length and shape. Tail contained two and 

 three-fifths times in the wing; the lateral feathers slightly graduated, the cen- 

 tral pair shorter than the next ones. Tarsus very short, only equal to the inner 

 toe without its claw ; stout, scarcely compressed, covered with minute reticu- 

 lations, except for a short space in front, which is scutellate. Outer toe about 

 equal to the middle ; its claw shorter than that of the middle ; middle claw 

 much dilated on the inner edge ; middle and outer claws slightly curved, not 

 very acute, upright ; inner claw very large, greatly curved, forming a semi- 

 circle, exceedingly acute, usually lying horizontal, not upright.* 



A very peculiar, though well known genus of Alcidse, without an intimate 

 ally except Lunda. The essential characters lie in the structure and config- 

 uration of the bill, the rictal and palpebral appendages, and the shape and po- 

 sition of the inner claw ; although there are other features involved. Lunda 

 is crested, with no furrow in the plumage, no palpebral appendages, and a 

 very differently shaped bill. 



Three distinct species represent the genus, as far as known. They are 

 all peculiarly boreal birds, not coming far south even in winter. One is ex- 

 tremely abundant on the shores of the North Atlantic ; another inhabits the 

 North Pacific exclusively ; another is more particularly a denizen of the Arctic 

 Ocean at large. They may readily be distinguished as follows : 



Species, (3). 

 I. A slender acute upright horn on the upper eyelid. Black of 



throat extending to bill 1. corniculaia. 



• The peculiar position, no less than unusual shape of the inner claw of this genus is a 

 strongly-marked character, not found in any other except Lunda. The great curvature 

 and extreme sharpness of the claw could not be maintained were it vertically placed like 

 the other claws, as it would be worn down by constant impaction against the rocks which 

 the birds habitually alight upon. But in the usual attitudes and movements of the birds 

 it lies perfectly flat on its side, and is so preserved intact. The birds make great use of 

 this claw in digging their burrows or in fighting ; and the preservation of the instrument 

 for these purposes is evidently the ulterior design of the peculiar direction of its axis. 

 The birds have the power of bringing it, on occasion for use, into a vertical position. 

 These facte, mayhap, are not generally known. See Pr. A. N. S., Phila., 1861, p. 254. 



[Jan. 



