ALCID.E — TlIK AUKS — FRATERCULA. 



^9Q 



extreme base ; gonys convex toward tlie base, strai^'hl, or even Roiuetiines slij,'hfly concuve, for 

 tlie terniiiial lialf, or more; tletidiious nasal sliic-.M lieeoniiny rapidly narrower toward the top; 

 terminal portion of the bill transversely suliyite ; base of the maxilla snrrounded by a deciduous 

 thickened horny rim, and rictus ornamented by a deeidiions tumid rosette ; eyelids furnished with 

 deciduous horny plates. No tufts about the head in the breeding-season. 



i''. arclica. 



The ileciduoua accc^aory pieces of the bill, together with the rictal and palpebral ornaments, 

 are cast at the close of the breeding-season.* 

 P'oUowing is a key to the known species. 



1. P. arctica. Hcjrny process of upper eyelid short, subconical ; grooves of the bill very 



oblique, broad, and distinct, the deciduous shields occupying not more than the busid 

 half of the bill. Chin and whole throat grayish. 



a. arctica. Bill and general size smaller. Culnien, 1. (iO-l. 90 inches ; gonya, 1.4t)-1.50 ; 

 depth of maxilla at l)ase, .75-.9(); of mandible, .40-..')0; tai-sus, 1.0()-1.I0 ; middle toe, 

 without claw, 1.25-1.40. Wing, 6.00-6.50. Hah. Coasts of the North Atlantic, from 

 Southern Greenland southward. 



/3. (jlacialis. Bill and general size larger. Culmen, 2.00-2.30 inches ; gonys, 1.40-1.60; 

 depth of maxilla at ba.se, .85-1.00 ; of mandible, .70-.80 ; tarsus, 1.10-1.35 ; middle toe, 

 without chiw, 1.45-1.60. Hah. Arctic Ocean, from Spitzbergcu to northern and western 

 (Ireeidand ; probably also western shores of Batlin's Bay, and Northern Labrador. 



2. F. oorniculata. Horny process of up])er eyelid narrow, elongated, horn-like ; grooves of 



bill nearly vertical, narrow, and le.ss distinct ; deciduous sinelds occupying much more 

 than the ba.sal half of the bill. Whole throat blackish, only the chin gray. Hah. Coasts 

 and islands of the North Pacific and Behring's Sea. 



* See Dr. Louis Bureau : Dp la M>ie du Bee ot des Oriiemcnts Palpebmnx du Mncarou.x nrctiquc, 

 Fralcrcnla arclica (Lin.), Stcph., npris la Snisoii dps Amours (Bidl. Soc. Zool. do France, 1878, pp. 1-21, 

 pis. iv. v.). 



