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SCIENCE. 



[N. S. Vol. V. No. 124. 



of much criticism, and whicli, under exist- 

 ing rules, it seems impossible to avoid. But 

 its inconsistencies are not the only objection 

 to the present system. From the nature of 

 the case, increase in knowledge as to the 

 interrelations of forms often shows that 

 those treated as full species really inter- 

 grade, and that closely related forms sup- 

 posed to intergrade really remain distinct, 

 necessitating corresponding changes from 

 a binomial to a trinomial, and vice versa. 

 Changes of this kind may be found in the 

 A. O. U. Check-List of North American 

 Birds by comparing the editions thus far 

 issued. 



It will be many years, even in America, 

 before it will be possible to say that certain 

 forms do or do not intergrade, and until 

 that time a fixed nomenclature will be im- 

 possible. 



In view of the objections to the present 

 system — incurable inconsistency, inevitable 

 changes with increase of knowledge, and 

 consequent delay in attaining a fixed nomen- 

 clature — and also in view of what to me 

 seems the logic of the case, it would appear 

 desirable to modify the system in the interest 

 of consistency, stability and common sense. 



In systematic zoology and botany a 

 knowledge of the degree of difference between 

 related forms is infinitely more important 

 than a knowledge of whether or not the in- 

 termediate links connecting such forms hap- 

 pen to be living or extinct. It would seem, 

 therefore, since it is is impossible for our 

 nomenclature to tell everything we wish to 

 know about a species, that it would serve a 

 more useful purpose if the terms species and 

 subspecies were so used as to indicate de- 

 gree of difi'erence, rather than the author's 

 opinion as to the existence or non-existence 

 of intergrades. It may be argued that ' de- 

 gree of difference ' is an elastic term, in- 

 capable of measurement and subject to the 

 same personal equation that besets the 

 present system. While this is to a certain 



extent true — since authors rarely see ob- 

 jects through the same spectacles— it is also 

 true that individual opinion as to whether 

 or not an observed degree of difference is 

 worthy of specific recognition would vary 

 within much narrower bounds than in the 

 alternative case of hypothetical intergrada- 

 tion ; and, further, that the change in nom- 

 enclature incident to the discovery of new 

 facts, inevitable under the old system, would 

 be entirely done away with. 



This leads to what is, after all, the most 

 practical consideration in connection with 

 the proposal to be governed by degree of dif- 

 ferentiation rather than intergradation in our 

 choice of binomial and trinomial nomencla- 

 ture, namely, the quantity of difference it 

 is desirable to accept as a measure of spe- 

 cific distinctness. Some authors, like Mr. 

 Lydekker in England, and Mr. Roosevelt 

 in this country, would have us limit the 

 number of species to types of groups, many 

 of which are commonly regarded by natu- 

 ralists as of subgeneric or even generic 

 weight. Among the larger mammals their 

 species are nearly always used in a super- 

 specific sense. Thus they would have one 

 large wolf, one small wolf, one black bear, 

 one large brown bear, and so on, urging 

 that the recognition of a number of related 

 species is inconvenient, interfering with the 

 clear and easy comprehension of the differ- 

 ent groups. Of course this is true, but since 

 the function of the naturalist is neither to 

 create nor destroy species, but to recognize, 

 describe and learn as much as he can about 

 those which nature has established, a diffi- 

 culty arises in carrying out their views of 

 classification. It is one thing to say — with- 

 out taking the trouble to find out the char- 

 acters that distinguish a batch of species — 

 what one thinks ought to be done for the 

 easier comprehension of the science ; a very 

 different thing to arrange the animals them- 

 selves in accordance with the species which 

 actually exist. 



