146 



SCIENCE 



[N. S. Vol. XXV. No. 630 



My friend Dr. Allen has given VuUur Lin- 

 naeus, 1Y58, as an example of elimination. 

 All authors may not agree with him in his 

 method of elimination, but I believe I am 

 justified in pointing out that both he and 

 those authors who differ with him as to his 

 method of elimination (for two methods are 

 possible in this case) have overlooked the very 

 important fact that they have ignored the 

 rule which Linnseus himself laid down for the 

 determination of types of his own genera. 

 Now, since Linnaeus did give a rule to be 

 applied to his genera, it seems to me that it 

 is obligatory to apply that rule to Linnaean 

 genera, regardless of our views of first species 

 or of elimination. The example upon which 

 the discussion is based is, therefore, an invalid 

 one from either Dr. Allen's or Mr. Stone's 

 point of view. 



A jjoint to which attention may be directed 

 is that, not only the elimination rule, but the 

 first species rule also is interpreted differently 

 by different men. Take the genus Disphara- 

 gus Dujardin, 1845, for instance. If an au- 

 thor who does not adopt the rule of type by 

 inclusion were to determine a type for this 

 genus, he might select either D. decorum or 

 D. laiiceps or D. tenuis as type, and yet he 

 would be following the first species rule, as 

 interpreted by three different sets of workers. 

 It should, however, be mentioned that if he 

 followed the rule as interpreted by the Amer- 

 ican Ornithological Union, this difference of 

 opinion would not arise; but not all first- 

 species men agree with the American Ornith- 

 ological Union interpretation. 



Still more important than the foregoing, is 

 the fact that the first species rule would in 

 many cases virtually misrepresent an original 

 author's intention, in that if the type is de- 

 termined on basis of his generic diagnosis and 

 with a number of species from which to select, 

 the nature of his genus becomes more or less 

 clear and we have a more or less definite sys- 

 tematic unit upon basis of which we can con- 

 fidently proceed with further work. If, how- 

 ever, the first species rule is made ironclad, 

 then not infrequently will the genus be based 

 upon a very imperfectly described species and 

 will thus be more or less obscure, hence fur- 



ther systematic work based upon such de- 

 termination unnecessarily runs the risk of 

 being only ephemeral in character. We would 

 thus make ourselves slaves to a rule of con- 

 venience (the convenience being judged from 

 only one standpoint), rather than make the 

 rules our servants. 



Again, in many groups there is an exceed- 

 ingly great advantage in taking a figured spe- 

 cies as type. In view of the possible necessity 

 of a future restudy of the anatomy of the 

 type species, in order to determine some point 

 which was not foreseen, it is often of great 

 importance to select as type a species which is 

 common and, therefore, easily obtained. Nor 

 should we forget DeCandolle's excellent ad- 

 vice as to the value of selecting as type a 

 species belonging to a group which contains 

 as large a number of species as possible, in 

 order to change as few names as possible. 

 These are other points of view in reference 

 to ' convenience,' points of view which are im- 

 portant not alone to the systematist, but also 

 to the morphologist, while the first species 

 rule ignores the morphologists entirely. 



In return for ignoring these points, the first 

 species rule presents to us one one-sided ad- 

 vantage. It is a rule of convenience — not of 

 principle, and as such it relieves an author 

 from knowing the literature when he attempts 

 systematic work. My very esteemed colleague, 

 Mr. Stone, expresses it, at least inferentially, 

 in another way, namely, he compares the first 

 species rule to arithmetic, hence he argues 

 that any one can use it, while the more com- 

 plicated methods he compares to higher mathe- 

 matics. The comparison is an excellent one, 

 and I accept it. But it may be remarked 

 that the question of type determination is one 

 which involves so many points that it should 

 not be entered into by any person whose edu- 

 cation has not extended beyond the arithmetic 

 stage; like astronomy, it calls for higher 

 mathematics; and to my mind the application 

 of the first species rule to type determination 

 will be found, when extended to all zoological 

 groups, to be about as satisfactory to the sys- 

 tematists at large, as would arithmetic be as 

 a final mathematical process in the case of 

 astronomy. 



