110 The American Naturalist. [February, 



It is on the question of description that a certain amount of 

 difference of opinion exists. From the codes of the Associa- 

 tions for the Advancement of Science, and of the Zoological 

 Congresses, no difference of opinion can be inferred, hut the 

 practice of a number of naturalists both zoologists and paleon- 

 tologists in America, and paleontologists in Europe, is not in 

 accord with the rule requiring definition of all groups above 

 species. It has always appeared to me remarkable that a rule 

 of such self evident necessity should not meet with universal 

 adoption. However, the objections to it, such as they are, I 

 will briefly consider. It is alleged that the definitions when first 

 given are more or less imperfect, and have to be subsequently 

 amended, hence it is argued they have no authority. How- 

 ever, the first definitions, if drawn up with reference to the 

 principles enumerated in the first part of this address, need 

 not be imperfect. Also an old time diagnosis of a division 

 which we have subsequently found it necessary to divide, is 

 not imperfect on that account alone, but it may be and often 

 is, the definition of a higher group. But you are familiar 

 with all this class of objections, and the answers to them, so I 

 will refer only to the positive reasons which have induced the 

 majority of naturalists to adhere to the rule. 



It is self evident that so soon as we abandon definitions for 

 words, we have left science and have gone into a kind of liter- 

 ature. In pursuing such a course we load ourselves with rub- 

 bish, and place ourselves in a position to have more of it 

 placed upon us. The load of necessary names is quite suffi- 

 cient, and we must have a reason for every one of them, in 

 order to feel that it is necessary to carry it. Next, it is essen- 

 tial that every line of scientific writing should be intelligible. 

 A man should be required to give a sufficient reason for every- 

 thing that he does in science. Thus much on behalf of clear- 

 ness and precision. There is another aspect of the case which 

 is ethical. I am aware that some students do not think that 

 ethical considerations should enter into scientific work. To 

 this I answer that I do not know of any field of human labor 

 into which ethical considerations do not necessarily enter. 

 The reasons for sustaining the law of priority are partly 



