MONOGRAPH OP THE PETRELS. 



four forms, which he distinguished with difficulty. In 1896 Salvin admitted the 

 same number of species, but relied principally on the presence or absence of lamellae in 

 the bill, and in their more or less pronounced development. The same four species are 

 admitted by Professor Reichenow, and after a prolonged study, I think that, for the 

 present at least, no alteration is advisable. I must, however, state that, in the large 

 series which I have examined in the British Museum and in the Rothschild Collection, 

 it has been impossible to define, from the characters of the width of the bill and its 

 lamellae, where one species ends and another begins, the connection between the broad- 

 billed Prion vittatus and the thin-billed P. desolatus being practically complete, if a large 

 series is examined. 



So far as is known, no two forms of these Blue Petrels nest on the same island, but 

 our knowledge is so limited that it would be unwise to alter the present determination. 



P. vittatus is exceedingly difficult to identify when only described as a species of 

 " Whale-bird " or " Blue Petrel," as they are called by sailors and travellers in the 

 accounts of their voyages, and consequently where no specimens have been obtained 

 at the time, it is impossible to say whether the bird observed was Prion vittatus or 

 P. banksi. Thus P. vittatus is said to breed abundantly in holes on the island of Tristan 

 da Cunha, and also on the Crozets, but the only specimen I have seen from the latter 

 group of islands was P. banksi, and this is the species which is thrown up in numbers 

 on the shores of Cape Colony after a storm. It should further be noted that some adult 

 and young birds brought by Captain Armson from the Crozets and given to Mr. E. L. 

 Layard, were identified by him as P. banksi (Ibis, 1867, p. 460). P. vittatus is also 

 said to breed on the basaltic cliffs of Heard Island and Inaccessible Island. 



A single specimen was obtained by the Scottish Antarctic Expedition on Gough 

 Island, where great numbers of Blue Petrels were seen in the vicinity, but others 

 which were shot were carried off by the voracious Skuas (Eagle Clarke, Ibis, 1905, p. 263). 



This Prion is included as an inhabitant of the Mascarenes Seas by the Rev. J. 

 Sibree {Ibis, 1892, p. 273). 



A specimen from Marion Island, collected by the " Challenger " Expedition, and 

 another obtained by Lord C. Campbell near the Crozet Islands during the same 

 voyage, were referred by Salvin to Prion vittatus, but they seem to be P. banksi, 

 though I admit that they are somewhat intermediate as regards the shape of the bill. 

 The true P. vittatus, together with the eggs, was obtained by Macgillivray on St. Paul 

 Island; these may be accepted as the first authenticated eggs of the Broad-billed 

 Prion. The species does not breed on Kerguelen Island, where P. desolatus seems to 

 take its place, but it must occur in the vicinity, as the Rev. A. E. Eaton found the skull 

 of Prion vittatus in the stomach of a Giant Petrel. The German Expedition on the 

 " Gazelle " met with the Broad-billed Prion at Kerguelen Island, but the American 

 " Transit of Venus " Expedition did not see it, nor did Mr. Hall recognise the species 

 on the island. 



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