MUSEUM OF COMPARATIVE ZOOLOGY. 131 



generally less, than those presented by specimens from different local- 

 ities on the same continent, where the species is admitted to be the 

 same ; sometimes not greater than is seen at the same locality. From 

 similar unsatisfactory comparisons, and undoubtedly in part from theories 

 of distribution, representatives from distant points in the United States 

 of species ranging from the Atlantic to the Pacific have been described 

 as distinct species. Not till large series of specimens from hundreds of 

 localities have been carefully compared can all these disputed points be 

 properly settled, through the tolerably exact determination of the in- 

 fluence of " locality on the individual " ; and we believe that no work 

 more important than this can at present be done. 



In this connection I can hardly avoid a word or two in reference to 

 the spirit which evidently incites many zoologies in their researcln--. 

 I refer, of course, to that eagerness for describing " new species " so 

 patent in all their publications,' — an influence highly derogatory to the 

 advancement of scientific knowledge. It tends to divert attention from 

 such a critical study of those species living in the naturalist's immediate 

 vicinity as will alone acquaint him with the amount of variation a 

 species may be expected to present.* Only by such a preparation can 

 one be prepared to estimate properly the character and value of differ- 

 ences presented by specimens from remote districts, of which onlv a 

 limited number of prepared examples can be examined. Almost all 

 writers on the different classes of Vertebrata have fallen in a greater or 

 less degree into the fault of describing species as new from either im- 

 proper or insufficient material, or of founding them on characters that a 

 critical study of numerous fresh specimens of a i'nw well-known species 

 w r ould have shown were of very slight, and often of even no value as 

 specific distinctions. The inquiry with many naturalists respecting 

 doubtful specimens seems rarely to be whether they may not be re- 

 ferred to some already known specie-, and the points of resemblance to 

 their nearest known ally accordingly carefully weighed against the differ- 

 ences, but rather are not they sufficiently different to warrant a descrip- 

 tion of them as new species? This greediness for species nova renders it 



* In respect to Birds, I have already called attention (Memoirs Bos. Soc. Nat. Hist , 

 Vol. I, p. 512) to the importance of collecting and comparing a very large nural e 

 specimens from the same locality, to learn the extent of the variation a species may 

 present at the same point; it is no less essential in Mammals, where seasonal varial 

 and those depending upon age are not always so evident. 



