146 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



Geographical Range. — Antarctic Seas. Falkland Islands. 



The Snowy Petrel was not obtained by the Princeton Expeditions to 

 Patagonia. The material in the Collection of the Academy of Natural 

 Sciences of Philadelphia, and also of the British Museum of Natural 

 History forms the basis of the description. 



The species presents a great scale of individual variation in size, that 

 apparently does not correlate with sex or age. Dr. Coues writing of this 

 feature says: "Independently of differences in absolute size of body, the 

 species presents unending variations in size, and, to some degree, in 

 shape of the bill. Specimens differ in this respect by as much as a fourth 

 of the whole length of the bill, which may be quite unaccompanied by 

 corresponding differences as to depth or width. The length of the nasal 

 tubes, and the amount of turgidity, and obliquity of truncation vary 

 greatly. Differences in the depth and robustness of the bill are surpris- 

 ingly great. 



"I have never seen, of many specimens, any which were referable 

 specifically from the typical form. But some individuals are so strikingly 

 small, that were it not for intermediate sizes, they might readily be sup- 

 posed distinct. Upon this character a variety niinov was founded by 

 Bonaparte, which has been adopted by so accurate and cautious an orni- 

 thologist as Dr. Schlegel " (Coues, Proc. Acad. Nat. Sci. Philad. 1866, pp. 

 160-161). 



"As we neared the edge of the pack ice a petrel which we had not 

 seen at the islands we had left became common [T. glacialoides), and as 

 soon as we reached the ice we fell in with the beautiful snow-white petrel 

 [Pagodroma nived), which is never to be found far from the antarctic ice. 

 The bird flies very much like the Whale Bird (Prion); it settles on the 

 water to feed ; it remains on the wing late at night when the other birds 

 have disappeared. I have seen birds flying about the ship as late as 1 1 

 o'clock at night, when it was quite dusk." Mosley's Notes, Nat. "Chal- 

 lenger," p. 253 (1879). 



The eggs of this petrel were obtained in numbers at the Duke of York 

 Island, Antarctic Ocean, by the "Southern Cross" Expedition. 



