Genus THALASSIDROMA. 
Gen. Cuar. Boll shorter than the head; much compressed in front of the nasal sheath, with 
the tip of the upper mandible suddenly curving and hooking downwards, and that of the 
lower one slightly angulated and following the curve of the upper. Nos¢ri/s contained in 
one tube or sheath, but showing two distinct orifices in front. Wangs long and acuminate, 
with the first quill shorter than the third, the second being the longest. Taz/ square or 
slightly forked. Legs having the tarsi rather long and slender, reticulated. Feet of three 
toes, united by a membrane; hind toe represented by a small, straight, dependent nail. 
FORK-TAILED STORM PETREL. 
Thalassidroma Leachii. 
Le Petrel de Leach. 
Tue first discovery of this Petrel in Europe is due to the researches of Mr. Bullock, who, in the year 1818, 
while on a tour through the northern and western isles of Scotland, found it breeding on the island of St. 
Kilda, whence he brought the original specimen from which M. Temminck took his description. In his 
‘ Manuel d’ Ornithologie,’ under the article alluded to, he dedicates the bird to Dr. Leach by the title of 
Procellaria Leachti. Since the period of its first discovery, when it appeared to be a bird of extreme rarity, 
it has been found, and that not unfrequently, on most parts of the British coast, and in the channel inter- 
vening between our island and the Continent. 
In its habits, manners, food, and nidification it so strictly resembles the Common Storm Petrel that the same 
description will serve for both. It differs from that bird, as also from all other European Storm Petrels, in 
being one of the largest in size, in having a forked tail, and remarkably short tarsi. 
The colour of the plumage is a sooty black, with the under tail-coverts and a patch on the rump white. 
COMMON STORM PETREL. 
Thalassidroma pelagica, Sedby. 
Le Petrel tempéte. 
Tuts, the least of web-footed birds, though by no means the least important, has been long celebrated by the 
name of ‘“ Mother Carey’s Chicken,” bestowed upon it by the British sailors, as the foreboder of storm and 
tempest to the mariner. 
The habits and manners of this singular group of birds may be described as being both nocturnal and 
oceanic. During the bright glare of day they conceal themselves in the crevices of rocks, stones, &c., from 
whence they depart on the approach of evening, and skim over the surface of the sea in search of food: 
approaching storms and dull murky weather also rouse them from their retreats to visit their congenial 
element; hence it is that when seen at a distance from the shore they intimate the approach of gales and 
severe weather. When out at sea they appear partial to the company of ships, which they follow for days 
together, and, surprising to say, are never seen to settle on the water; in fact, the only period of rest they 
appear to allow their organs of flight is while, with extended wing, they skim, half flying half trippmg, over the 
surface of the billows; and it would appear as if the bones of the legs were expressly formed for this manceuvre, 
being sufficiently flexible to bend without breaking to any opposing pressure or sudden concussion. While 
skimming around ships they pick up any refuse oily matters that may be thrown overboard, and also any of 
the small mollusca that may be brought to the surface by the agitation of the water which the vessel occasions 
in her progress. . 
The Common Storm Petrel is abundant over the whole of the northern seas of Europe, especially in the 
rocky islands of Scotland, where it breeds in the crevices of rocks, among loose stones, and occasionally in 
holes on the ground, generally laying a single egg of a pure white. The young remain in their retreats 
until their pinions are sufficiently strong for flight, and it is a considerable period before they are able to 
follow their parents. 
The adults of both sexes are alike in plumage, which is invariably of a sooty black, with a white spot on the 
rump; the bill and tarsi black. 
We have figured an adult of each species, of the natural size. 
