PROCELLARIID^. 255 



by Gray, in the British Museum, are quite differently coloured, and, if Gray's 

 view be correct, represent the white-breasted form of this bird. Other 

 possible instances will suggest themselves of members of this family of birds 

 presenting this double form of colour. But, as I have already said, the whole 

 question is eminently one that must be solved by observation rather than by 

 speculation ; and so, with the hint here thrown out, I leave it for the 

 present. 



The describers of Q?. trinitatis state that it belongs to that section of 

 the genus distinguished by Bonaparte as Pterodroma ; but if there be any 

 truth in what I have just said, this determination must be reconsidered 



(ESTRELATA DEFILIPPIANA. Plate XXXIII. 



JUstrelata defilippiana, Gigl. & Salvad. Ibis, 1869, p. 63 ; iid. Atti Soc. Ital. Sc. Nat. xi. 

 p. 453 ; Gigl. Faun. Vertebr. nell^ Oceano, p. 43. 



(E. pileo, coUo supra, dorso ac supracaudalibus pulclire cinereis, uropygio ac regione periophtbal- 

 mica, presertim infra oculos, nigricantibus, plumis dorsalibus obsolete albescente marginatis ; 

 sineipitis plumis albo marginatis, fronte fere ex toto alba ; subtus omnino pure alba, lateribus 

 pectoris ciaereo tinctis ; alis cinereo-nigricantibus, remigibus secundariis magis cinereis, 

 fasciam obliquam fere constituentibus ; tectricibus alse inferioribus candidis ; margine carpali 

 ac linea sub margiae radiali candido cinereo-nigricantibus ; remigibus nigricantibus, duabus 

 tertiis partibus pogonii interni abrupte albis, iutus apicem versus fusco-nigricante marginatis ; 

 rectricibus sex mediis fere ex toto pure cinereis, quarta et quinta utrinque albo variegatis, 

 extima alba pogonio externo minutissime cinereo-punctata, interdum pure alba ; rostro 

 nigi'o, tarsis pallide cteruleis, digitis nigris, palamis flavidis apicem versus fuscis; iride 

 brunnea : long. tot. ll'O, alse 9'0, caudse 3-8, rostri a fronte 1-04, a rictu 1-4, tarsi 1-07, dig. 

 med. cum ung. 1'4. 



Hab. in Oceano Pacifico meridionali orientali [Giglioli) . 



Dr. Giglioli first saw this species on the 5th of August. It followed the 

 wake of the ' Magenta ' up to the 10th of the same month, in lat. 18" 4' S., 

 long. 79° 35' W., not far from the Peruvian coast. It reappeared more 

 numerously, following the ship's wake, during the cruise from Callao to 



