MONOGRAPH OF THE PETRELS. 



Ocean, along the coast of America to Chile and Peru. On comparing a series of 

 specimens from northern and southern latitudes, I cannot find any difference in colour 

 or markings ; in both there are occasional examples with whitish edgings to the wing- 

 coverts, but these are apparently a sign of immaturity, as with other Storm-Petrels. 



As regards any difference in size between northern and southern individuals, it may 

 be mentioned that eleven specimens from the coast of Massachusetts measure as 

 follows : — 



cf Wing, 5.5-6.0 inches ; tarsus, 1.3-1.4 inch. 

 ? Wing, 5.2-6.2 inches ; tarsus, 1.3-1.4 inch. 



Twelve specimens from the Antarctic Pack Ice and South Victoria Land give 

 the following measurements : — 



cf Wing, 5.8-6.2 inches ; tarsus, 1.25-1.35 inch. 

 $ Wing, 6.0-6.35 inches ; tarsus, 1.3-1.35 inch. 



It is evident, therefore, that there is no distinction in size between specimens 

 from northern and southern latitudes. 



Since Professor Giglioli wrote, our knowledge of the distribution of Wilson's Petrel 

 has been greatly increased by the observations of the naturalists attached to the ex- 

 ploring ships which have visited the Antarctic continent, and the species has been 

 found nesting there as well as on Kerguelen Island, the South Shetlands, and South 

 Orkney Isles. Mr. Howard Saunders has given the following excellent summary 

 of the southern range of 0. oceanicus in the "Antarctic Manual" (p. 235) : — " It was 

 observed by Dr. McCormick hovering, like a Swallow or Martin, over the mast-head of 

 the ' Erebus,' when in the pack ; and, on the third attempt to go southwards, 

 examples (now in the British Museum) were obtained off Louis Philippe Land, in 

 January, 1843. These birds were evidently incubating at no great distance, as their 

 breasts were bare of feathers. Surgeon Webster, of H.M.S. ' Chanticleer,' refers to the 

 abundance of this species at Deception Island, one of the South Shetlands. The 

 ' Belgica ' obtained specimens in Gerlache Strait in January, 1898, as well as in the Pack 

 at about 70° S. Lat. and 87° W. Long., in January, 1899. The ' Challenger ' expedition 

 secured several off the Ice Barrier in February, 1874, and examples were obtained during 

 the voyage of the ' Southern Cross ' between 63° and 66° S. Lat., and 161° and 166° E. 

 Long." 



The species was discovered by the naturalists of the latter expedition breeding 

 on Cape Adare. Mr. L. Bernacchi observed it every day during the passage of the 

 " Southern Cross " through the Pack Ice, and as far south as the Great Ice Barrier. 

 He records it as nesting high up on the mountain sides of South Victoria Land. Mr. 

 Nikolai Hanson, the zoologist on the " Southern Cross," remarked that it disappeared 

 from there early in March. 



Several specimens were obtained during the voyage of the " Discovery," and 

 Dr. E. A. Wilson says that the bird is evidently a migrant to the Antarctic Ocean, 



42 



