Order ANSERES.l [Fam. PROCELLARIID^. 



THALASSIDROMA NEREIS. 



(GREY-BACKED STORM-PETREL.) 



Thalassidroma nereis, Gould, P. Z. S. 1840, p. 178. 

 Procellaria nereis, Bonap. C. R. xlii. p. 769 (1856). 



Ad. pileo colloque toto, cum interscapulio et tectricibus alarum minimis, et medianis exterioribus fuliginoso- 

 nigris : dorso postico, uropygio et supracaudalibus, scapidaribus et tectricibus alarum majoribus 

 canescentibus : remigibus brunnescenti-nigris, secundariis vix canescente lavatis : Cauda sordide canes- 

 cente, ad apicem nigricante : gutture pallidiiis fuliginoso : eorpore reliquo subtiis albo, subalaribus exte- 

 rioribus brunneis : rostro nigro, versus basin mandibular albicante : pedibus saturate brunneis : iride 

 nigra. 



Adult. Head, neck, and all the upper surface dark ash-grey; rump and upper tail-coverts paler, or 

 sdvery grey ; under surface pure white, the grey plumage presenting a distinct margin across the upper 

 part of the breast. Irides and bill black, the latter whitish towards the base of lower mandible j 

 legs and feet dark brown. Length 6'5 inches; extent of wings 13 ; wing, from flexure, 5"5 ; tail 2'75 ; 

 bill, along the ridge "5, along the edge of lower mandible "55 ; bare tibia "6 ; tarsus 1*3 ; middle toe 

 and claw 1. 



There is a single example of this rare species of Storm-Petrel in the Canterbury Museum. 



It was originally discovered and described by Mr. Gould, who obtained four specimens 

 during a calm on his passage from Hobart Town to Sydney in May 1839, and who met with it 

 again a month earlier in the following year between New South Wales and the northernmost 

 point of New Zealand. This naturalist informs us that the sexes are alike in plumage, and do 

 not present any material difference in size. 



The species is readily distinguishable from the other Storm-Petrels by the absence of white 

 on the rump. 



