MONOGRAPH OF THE PETRELS. 



the wing, however, is broader and blacker in P. dbscurus, being narrower, browner, 

 and more broken up in P. auduboni. In the " Biologia Centrali- Americana " 

 (Aves, III., p. 436) it is stated that P. auduboni is rather smaller than P. obscurus, 

 but this now appears to be doubtful. Five specimens of P. auduboni measure as 

 follows: Wing, 7.7-8.0 inches; culmen, 1.1-1.2; tarsus, 1.55-1.6; middle toe and 

 claw, 1.55-1.95. 



In P. obscurus from the Pacific Islands, the measurements are as follows : Wing, 

 7.3-8.1 inches ; culmen, 1.0-1.2 ; tarsus, 1.45-1.6 ; middle toe and claw, 1.65-1.85. 



The measurements of these two forms afford no characters for specific separation, 

 though P. auduboni would appear to have a slightly longer tarsus than P. obscurus. I 

 find that the chief difference between the eastern and western birds lies in the browner 

 colour of P. auduboni, which is never so black as P. obscurus. The patch above the 

 thighs is brown in the former bird, not black, and the band round the edge of the wing 

 below is browner, and less distinct than in P. obscurus. 



The specimen from Montserrat in the British Museum, collected by Mr. Sturge 

 (P. Z. 8., 1879, p. 765), is blacker than the ordinary specimens of P. auduboni, and 

 closely resembles P. obscurus. 



Audubon's Shearwater is a species of Eastern North America. The A. O. U. 

 " Checklist " gives the range as from the warmer parts of the Atlantic, incidentally 

 northwards to New Jersey and Long Island. It breeds on the Bermudas and 

 Bahamas (Andros Island), San Domingo, Montserrat, and other West Indian islands, 

 as far south as the island of Grenada. 



Mr. J. M. Jones in his " Naturalist in Bermuda " (1859), gives an interesting account 

 of the species, which, in 1849, bred on " Black," or " Gurnet-head " Rock, where eggs 

 and young were taken by Captain Orde and Captain McLeod {I.e., p, 55). Dr. Percy 

 Lowe, who accompanied Sir Frederick Johnstone on his yacht, the R.Y.S. " Zenaida," 

 to the Bermudas, in May, 1907, procured a female of P. auduboni with its egg, and 

 was informed that this was the first occasion of its nesting on the islands for many 

 years, though it did so formerly in large numbers. 



Audubon states that on the 26th of June, 1826, when becalmed in the Gulf of 

 Mexico, off the western coast of Florida, he found the species numerous. In the 

 West Indies it has been procured off the island of San Domingo by Dr. Bryant, and 

 Mr. C. B. Cory says that, though he did not himself observe P. auduboni in that island, 

 he saw a number at sea about twenty miles to the north of Tortuga Island. 



Dr. J. G. Wells relates {Auk, 1889, p. 19), in a letter to Mr. G. N. Lawrence, that 

 young birds of a " Diablo tin " had been brought to the market at Greenville, Grenada 

 Island, for sale : the natives stating that they had been captured in holes on a small 

 island to the eastward called " Mouchoir Quarre." He himself afterwards visited a 

 small islet called Labaye Rock, about a mile off the Port of Greenville, on the 2nd of 

 April, 1888, and procured adult birds, nestlings, and an egg. He says that it is 



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