MONOGRAPH OF THE PETRELS. 



Gould's original description of his T. tropica is as follows : — " Head, back, wings, 

 tail, and breast dark sooty-black ; chin, under-coverts of the wings, abdomen, flanks, 

 under tail-coverts and a broad crescentic-shaped band across the upper tail-coverts, 

 snow-white ; bill, feet, and legs black. Total length, 7| in. ; bill, •£ in. ; wing, 6 \ in. ; 

 tail, 31- in. ; tarsus, If in. ; middle toe and nail, \\ in." The white abdomen would 

 seem to point to P. tropica being identical with C. grallaria, but then Gould would 

 scarcely have omitted to mention the conspicuous white edgings on the feathers of 

 the back. 



Gould further writes of his T. tropica : — " I observed this species in the Atlantic, 

 where it is confined to the equatorial region, being most abundant in the vicinity of the 

 Line. It is the largest member of the genus with which I am acquainted, and is 

 rendered very conspicuous by the white mark on its throat " (cf. Ann. Nat. Hist., XIII., 

 p. 366). In his folio work on the " Birds of Australia " he does not allude to T. tropica 

 at all, nor does the name occur in his "Handbook," but in both these works he gives the 

 following note under the heading of C. grallaria : — " I killed specimens of a nearly 

 allied species within the tropics of the South Atlantic, which differed in being of a 

 larger size, and in having a patch of greyish white on the throat. These differences will 

 doubtless prove it to be a distinct species, and I mention this in order that the two 

 birds might not be confounded by subsequent voyagers or writers on the subject. I 

 have presented a specimen of the larger species, killed by myself, at the Equator, to 

 the British Museum, where it is always accessible for comparison and other scientific 

 purposes." 



The example mentioned by Gould is specimen a of Salvin's " Catalogue of Birds " 

 (Vol. XXV., p. 365), and bears the label " North Atlantic, Lat. 6° 33' N, Long. 18° 6' 

 W." The measurements are : — Wing, 6.7 inches ; culmen, 0.55 ; tarsus, 1.6 ; middle 

 toe and claw, 1.15. 



It will be seen that these dimensions differ somewhat from those of C. tropica, 

 given by Gould, and the actual type of the latter species no doubt went to Philadelphia 

 with the rest of his collection ; but the specimen in the British Museum may 

 justly be considered a co-type of C. tropica, and Salvin has recognised it as such. Gould 

 certainly regarded it in this light, and his intention evidently was to deposit in the 

 National Collection an authentic example of the supposed species from the Equator, 

 but he did not present it under his previous name of T. tropica, although there can be 

 no doubt that it is the species which he described under that title in 1844. 



This specimen is unquestionably an immature individual of C. melanogaster. 

 It is in no case C. grallaria, and the scanty edgings of white to the dorsal feathers are 

 but evidences of immaturity ; while on the abdomen are some patches of black, also, 

 in my opinion, signs of a young C. melanogaster, and clearly showing that it 

 cannot be referred to C. grallaria. It is remarkable that Gould makes no allusion 

 to these black patches in the specimen he gave to the British Museum. 



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