5038 Letters on Natural History. 



white, with scarce any yellowish or grayish ; the dark markings be- 

 neath the same bistre-brown as the back : this I conceive to be the 

 great-footed falcon of Audubon, Wilson, &c; it is the rarest of all the 

 varieties, and useless for hawking, being spiritless and cowardly. 

 The third or common variety is intermediate between the other two.' 

 This I consider a valuable communication, as Strickland, besides his 

 ornithological knowledge, is conversant with falconry, and has tra- 

 velled much in Norway, where the birds abound. 



" Both the forktailed petrel and the common storm petrel have been 

 more common than usual inland this year, in consequence of the 

 storms. The common species I have often seen out at sea in blowing 

 weather, following in the ship's wake, with a low incessant wailing cry 

 of ' weet, weet: ' they skim on the surface in the manner represented 

 in Bewick's plate, except that the wings are always expanded, whereas 

 he shows them closed. I never saw them at sea in calm weather, and 

 hardly ever within sight of land : I once saw one nearly opposite 

 Swansea, in the Bristol Channel, in very stormy weather, but the 

 sailors regarded it as an uncommon occurrence, and said that they 

 were scarcely ever seen above the Lundy Island. Procellaria Leachii, 

 of which you say you have a specimen, breeds in the Hebrides, parti- 

 cularly St. Kilda. I never saw the storm petrel actually swim, though 

 they keep their feet almost in the water while skimming as I men- 

 tioned above. There are two other species of storm petrel, besides 

 P. pelagica and P. Leachii; one of them, P. oceanica, found in the 

 South Pacific, and distinguished by the comparative length of the 

 tarsi; and the other, P. Americana, on the coasts of North America. 

 These four nearly allied species have been separated by Mr. Vigors 

 as a distinct genus from the true petrels, under the name of Thalassi- 

 droma. 



" I congratulate your Western district on the accession of that 

 beautiful songster the blackcap to its Fauna ; but I am afraid I shall 

 not be able to furnish you with much information on your favourite 

 group, the Sylviadae, as I am ashamed to say that I am far less inti- 

 mately acquainted with them than with many other less common 

 groups. The greater pettychaps or fauvette I remeaober to have 

 heard frequently about seven or eight years since, in the park at Lit- 

 tlecote, Berkshire, the seat of General Popham ; but the bird is sel- 

 dom seen, as it lies in thick bushes, whence it is almost impossible to 

 drive it : the song is most beautiful, but very difficult to identify or 

 describe, as it consists in a great measure of imitations of the song 

 of the other birds, in which species of mockery it is, I think, unri- 



