49 



of some naturalists come very near to, but do not quite arrive at, the i-ank of 

 species ; oi', again, between sub-species and well marked varieties, or between 

 lesser varieties and individual differences."* 



Mr. Sclater, in bis review of Gould's Monograph of the Trochilidm, 

 observes, — " We have never been able to di^aw the line between a species and 

 a climatic variety, nor do we believe it is possible so to do. We therefore do 

 not complain of Mr. Gould having given sj)ecific names to certain local forms, 

 if it can be shown that they are invariably distinguishable by constant charac- 

 ters, "t And another well known naturalist, Mr. A. K Wallace, in writing 

 on the Pigeons of the Malay Archipelago says,^ — " A permanent local variety 

 is ail absurdity and a contradiction, and if we once admit it, we make species 

 a matter of pure opinion, and shut the door to all uniformity of nomenclature;" 

 and he holds that where the difference, however trivial, is constant, the so-called 

 varieties must be regarded as distinct species. 



Practically, as it seems to me, it matters little whether these closely allied 

 forms be characterized as species, races, or varieties, the true object of all 

 nomenclature being to aid the student in the systematic arrangement of all 

 existing oi'ganisms according to their natural affinities. But the too common 

 practice of confounding well marked local forms on the mere supposition of 

 specific identity, without actual examination and comparison, is a positive 

 injury to the cause of science, and cannot be too strongly condemned. It is 

 not only fatal to scientific accuracy, but renders it almost hopeless to arrive at 

 correct conclusions on the geographical distribution of species, a subject of the 

 highest interest to the philosophical naturalist. 



13. Nestor EssLmoii, De Souance. 



What is Nestor Esslingii ? asks one of my correspondents. The question, 

 though simple enough in itself, is not easily answered. The only specimen 

 extant, so far as I am aware, is the one in the British Museum (which I have 

 never had an opportunity of examining), and the several accounts given of 

 the bird by those who profess to describe it, are so much at variance that local 

 naturalists may well acknowledge themselves at fault respecting it. 



M. de Souance, the original describer of the species, says : — 



" Le ISTestor dont nous allons donner la description est, sans contredit, 

 I'oiseau le plus remarquable de la collection Massena. Intermediaire entre le 

 N. hypopolius et le N. productus, ce magnifique Perroquet reunit, dans son 

 plumage, des details caracteristiques de ces deux esp6ces. Coloration g^nerale 

 semblable a celle du N. hypopolius." 



Mr. Gould, in the Supplement to his Hand-hook to the Birds of Australia, 

 says of this species, — " A single specimen only of this magnificent Parrot has 



* Orir/m of Species, p. 60. + Ibis, 1862, p. 73. 



