64 Drs. Gio;lioli and Salvador! on 



o' 



peared more numerously, following the ship's wake, during our 

 cruise from Callao to Valparaiso in September. It flies very 

 much like a Prion. Bill black ; tarsi light blue ; toes black, 

 interdigital membranes yellowish, brownish towards the distal 

 extremity; irides brown." — H. H. G. 



j^. pileo, eollo supra, dorso ac supracaudalibus pulchre cinereis, 

 uropygio ac regione periophthalmica, prsesertim infra oculos, 

 nigricantibus ; plumis dorsalibus obsolete albescente margi- 

 natis ; sincipitis plumis albo marginatis, fronte fere ex toto 

 alba: subtus omnino pure alba; lateribus pectoris vix cine- 

 reo tinctis ; alis cinereo-nigricantibus, remigibus secundariis 

 magis cinereis, fasciam obliquam fere constituentibus ; tec- 

 tricibus alse inferioribus candidis; margine carpali ac linea 

 sub margine radiali candido cinereo-nigricantibus, remi- 

 gibus nigricantibus; duabus tertise partis pogonii interni 

 abrupte albis, intus apicem versus fusco-nigricante margi- 

 natis. Rectricibus sex mediis fere ex toto pure cinereis, 

 quarta et quinta utrinque albo variegatis, extima alba po- 

 gonio externo minutissime cinereo-punctata, interdum pure 

 alba ; rostro nigro ; tarsis pallide cseruleis, digitis nigris, 

 palamis flavidis apicem versus fuscis ; iride brunnea. 

 Long. tot. 0°»-300, al^ 0'^-225-0°i-240, caud. 0'"-105-0"i-120, 



rostr. a fronte 0°i-026-0'^-029, tars. 0"i-028-0ni-029, dig. med. 



cum ung. 0«^-035-0°i-037. 



Besides these slight differences in size, there are in the four 

 specimens collected slight diff'erences in colour, especially in the 

 external rectrices, which are more or less spotted with greyish — 

 sometimes the first is quite white. This species, although 

 much smaller than JE. mollis (Gould), has a bill relatively, and 

 in some specimens, absolutely longer. It is much compressed, 

 and the interramal space denuded of feathers, as in Prion, with 

 which this species appears to have some affinity in the coloration 

 of the tarsi and the manner of flight, as already noticed. 



jE. defilippiana belongs to that group of small species dis- 

 tinguished by their white under wing-coverts, and to which be- 

 long JE. cooki (Gray), ^. gavia (Licht.), JE. desolata (Gm.), and 

 JE. gularis, Peale* ; with this last species alone our bird has in 



* This species was incompletely described by Peale (Zool. U. S. Expl. 

 Exp. 1848, p. 299, pi. 84) ; but the type specimen has been most accu- 

 rately redescribed by Coues (Proc. Acad. Philad. 1866, p. 151), who, for 

 want of specimens for comparison, did not consider it specifically distinct 



