RAZOR-BILL AUK. 233 
developed to its greatest known extent. It consti- 
tutes the 
Genus Fratercula, Brisson. — Generic charac- 
ters . — Bill short, depth of the head, triangular, 
compressed; culmen arched, furrowed trans- 
versely, corners of the mouth with a dilatable 
skin ; nostrils basal, a narrow linear slit placed 
close to edge of maxilla ; wings short, nar- 
row, accuminato ; legs placed behind ; tarsi 
short, feet rather small, claws hooked and 
sharp, hallux wanting. 
Types. — F. arctica. — Europe, America. 
Note Gregarious ; breed in burrows, or under 
rocks, in fissures, &c. 
