GuILLEMoT, NATATORES. URIA. 421 
Tue above list of provincial appellations, bestowed upon Periodical 
the Guillemot in different parts of Britain, is a sufficient aaa 
proof of its general distribution and frequent occurrence. 
It is in fact (at least during the summer or breeding season), 
to be found throughout the whole extent of our coasts, con- 
gregated in large bodies, wherever the shores offer a precipi- 
tous rocky barrier, or islands occur, affording fit places for 
its reproduction. Such are the ledges and clefts of rocks, 
where these birds incubate close to each other; making no 
nest, but each depositing its large solitary egg upon the bare Incubation, 
and often sloping surface, along which it is secured from roll- ““ 
ing by its conical shape, being very large at one end, and ta- 
pering rapidly towards the other; thus, when disturbed, 
merely describing a circle within its own length. The ege 
varies in colour and markings, but the prevailing tint is a 
fine verdigris-green, blotched with brownish-black. White 
varieties, without or with few spots, also frequently occur. 
Incubation lasts for a month, and when the young are first 
excluded, they are covered with a thick down, of a blackish- 
grey colour above, and white beneath. This gradually gives 
place to the regular plumage, and in the course of five or 
six weeks from the time of hatching, they are capable of 
taking to the water. During the time they remain upon the 
rock, the parents supply them plentifully with the young of 
the herring, and herring-sprats, which form the principal 
food of this and other species belonging to the Alcada. Up- Food. 
on the Northumbrian coast these Guillemots breed in great 
numbers on the Fern Islands, a locality that has afforded me 
ample opportunities of attending to their economy, and watch- 
ing the changes they undergo. They have here selected the 
summits of three fine isolated pillars, or masses of whinstone 
(trap-rock), that rise upwards of thirty feet above the level 
of the sea. Upon these the eggs are laid as close as possible, 
merely allowing room for the birds to sit upon them, which 
they do in an upright position. The appearance they make 
when thus seated in a dense mass, is curious, and the interest 
