NATATORES. 



455 



much darker head, neck, and upper surface, and a uniform- 

 coloured tail, whereas Mr. Gray's P. cooki has the inner webs 

 of the outer tail-feathers snow-white. It is impossible to say 

 to which of these two birds the P. velox of Solan der's draw- 

 ings has reference, and consequently that name will neces- 

 sarily sink into a synonym. 



The Australian seas abound with Petrels, the investigation 

 of the various species of which, their habits and economy, as 

 well as their places of abode, will serve to occupy the atten- 

 tion of ornithologists for years to come. It could scarcely be 

 expected that a single voyage to Australia could add much to 

 our knowledge of the subject ; my readers must therefore be 

 contented with little more than an illustration. 



That, like the other members of the genus, it subsists upon 

 small fishes, medusae, and others of the lower marine animals, 

 there can be no doubt. 



I have been informed that this species breeds in abundance 

 on one of the small islands near the mouth of the harbour of 

 Port Stephen, in New South Wales, where my specimens were 

 procm'ed. I frequently saw it during my passage from Syd- 

 ney to Cape Horn, but it was most numerous between the 

 coast of Australia and the northern part of New Zealand. It 

 is one of the most elegantly formed species of the genus, and 

 is rendered conspicuously different from the rest of its con- 

 geners by its white abdomen and under wing-coverts, which 

 show very conspicuously when the bird is on the wing, parti- 

 cularly when seen from beneath, as it frequently may be when 

 the breeze is fresh or a gale rising ; it seldom, however, even 

 then mounts higher than the vane of the vessel. 



The sexes do not differ in external appearance. 



Crown of the head, all the upper surface, and wings dark 

 slaty black ; tail slate-grey ; greater wing-coverts slightly 

 fringed with white ; face, throat, all the under surface, the 

 base of the inner webs of the primaries and secondaries, and 

 a line along the inner edge of the shoulder pure white ; bill 



