Mas-afuera and Juan Fernandez. 373 



seHcea (Less.) . Having searched in vain for a name appli- 

 cable to this bird, I am obliged to bestow a new one upon it, a 

 course I should take with more reluctance did it not possess 

 characters well defined for this intricate group of birds. 



CESTRELATA EXTERNA, Sp. U. 



Supra plumbeo-nigra, plurais omnibus intiis albis, collo postico 

 fere albo, plumarum apicibus pallidissime griseis, scapu- 

 larium et dorsi plumarum marginibus griseis ; supracau- 

 dalibus lateraliter griseis ; fronte, corpore subtiis et pa- 

 gina alarum inferiore pure albis; remigibus plumbeo- 

 nigris, intiis nisi in apicibus albis ; rectricibus lateralibus 

 obscure griseis, in pogonii interni dimidio basali albis, 

 omnium apicibus obscurioribus ; rostro nigro, tarsis et 

 pedibus flavis, horum dimidio terminali nigro : long, tota 

 16, alse Wo, caudee 5, tarsi 1"4, rostri a rictu 1*8, dig. 

 med. 1-9. 

 In order to be sure that the present bird was not referable 

 to that described by Lesson (Man. ii. p. 402) as Pujffinus 

 sericeus, I sent the single adult specimen to Dr. Oustalet, 

 asking him to compare it with the type of Lessou^s descrip- 

 tion, preserved in the Museum of the Jardin des Plantes. 

 This he most obligingly undertook, and wrote me the follow- 

 ing letter. This not only shows that (E. externa must be 

 considered quite distinct from P. sericeus, but conclusively 

 points out the proper position of the latter bird to be in the 

 genus (Estrelata, and not in Puffinus, as placed by Lesson, 

 nor in Adamastor, to which genus it was assigned by Bona- 

 parte, to whose determination Dr. Coues assented. The tarsi 

 compressed in Puffinus, more " quadrilateral " or Lariform in 

 (Estrelata, show characters that have not received the atten- 

 tion due to them. By them these two genera [Adainastor 

 resembling Puffinus) can be recognized without fail. 

 Dr. Oustalet^s letter is as follows : — 



Museum d'Histohe Naturelle, 



Paris, 2 Juin, 1875. 



Cher Monsieur, — J'ai compare attentivement Foiseau que 

 vous m'avez envoye avec le type du Puffinus sericeus, Less., 

 et je me suis convaincu que les deux oiseaux sont complete- 



