CAuk 

 Oct. 



"It was my misfortune Inst summer to feel called upon to criticise some 

 recent ornithological work in which the process of recognizing subspe- 

 cies had been carried to the extreme, and my opinions were published in 

 Science, August 8, 1902, under the heading 'So-called Species and Sub- 

 species.' In the same journal, September 5, Dr. J. A. Allen, the well 

 known zoologist, criticised my opinions as those of a layman, and emphat- 

 ically denied two of my main contentions. As nothing is gained by news- 

 paper controversy, I made no reply, but the questions involved are 

 extremely important and after six months further consideration of them, 

 I have decided to set forth what seem to me some of the fundamental 

 rules, which ought to govern work in systematic zoology. First, how- 

 ever, as Dr. Allen has challenged my right to opinions on the subject, it 

 is only fair to say that, although I have never described a new or sup- 

 posedly new bird, I have had occasion to examine carefully several thou- 

 sand specimens of echinoderms, and have been under the necessity of 

 naming a number of new species in that group, so that I am not an entire 

 stranger to the numerous perplexities of the systematist, to which Dr. 

 Allen refers. Now I freely admit that from the systematist's point of 

 view, birds are more perplexing than echinoderms, and that Dr. Allen, 

 both because of his naturally judicious temperament and by his many 

 years of experience amid exceptional opportunities, is far better qualified 

 to discuss this subject than am I. Yet I do feel, that whether the animal 

 be a bird, a fish, a worm or an infusorian, the essential principles of sys- 

 tematic zoology ought to be the same in all cases, and that any zoologist 

 who has wrestled honestly with the knotty problem of specific distinctions 

 is entitled to opinions on the subject. I therefore venture to state some 

 of these essential principles as they appear to me. 



" /. Characters which are not sufficiently conspicuous, so that they can 

 be stated in language or figures of some sort, ought not to be made the 

 basis of a new name. 



"This principle appears so axiomatic that an apologj' would be made for 

 stating it here, if it had not been seriously questioned by Dr. Allen. He 

 says: 'In ornithology, and especially in mammalogy, perfectly "good 

 species " are often so similar in size and color that even the expert cannot 

 satisfactorily identify them from descriptions, and hence, almost from 

 time immemorial, direct comparison with authentic material has been 

 necessary in order to settle such difficult cases. As all experts in 

 this line of study well know, forms that may be indistinguishable by 

 descriptions are, when brought together, and especially when series are 

 compared, so noticeably different that there is no trouble in distinguish- 

 ing them at a glance.' Now I confess that after giving these words careful 

 thought I am unable to believe that the validity of my contention is 

 affected. I am utterly unable to conceive of two objects, which I could 

 ' distinguish at a glance,' the differences between which would be so 

 intangible that I could not state them ' in language or figures of some 

 sort.' As to the comparison of specimens with types or other authentic 



