May 21, 1909] 



SCIENCE 



815 



species in parentheses, without describing it. 

 As defined, the genus was based on but one or 

 two general diagnostic characters. Just re- 

 cently, I had occasion to deal with the genus 

 in connection with certain parasites of the 

 common house-fly (Musca domestica Linnaeus) ; 

 the species of parasite agreed with the brief 

 description of the genus in every particular, 

 as far as it went. The question arose, was it 

 the type species. To decide from the descrip- 

 tion of the genus was nothing less than pure 

 guesswork. The generic description or diag- 

 nosis did not characterize the species. For- 

 tunately, I knew that the type spiecies was in 

 the National Museum at Washington and 

 through the kindness of the authorities of that 

 institution I learned that the species which 

 I had under consideration was not only not 

 the type species of Pachycrepoideus — a fact 

 which was not strange — but that it differed so 

 much from the genus itself, in other struc- 

 tural, generic characters not mentioned in the 

 description, that it formed a distinct genus 

 in the same division of the tribe.'' This case 

 is but one in a number of similar ones which 

 occur in the parasitic Hymenoptera. To say 

 that the type species of this genus is described 

 is to say, it seems to me, that naming a thing 

 describes it. To hold such a view is to recom- 

 mend the practise of naming instead of de- 

 scribing, which is practically what the case 

 just cited amounts to. It is merely another 

 way of saying that to generalize on the whole, 

 is describing and making recognizable all of 

 the component parts. As genera are being 

 described at the present day, even, the practise 

 is a most dangerous one, for unless the type 

 species are soon described they become unrec- 

 ognizable, the genera practically come under 

 the first class of cases considered, and progress 

 demands a removal of the obstructions and 

 they fall or have to be reconstructed. Future 

 cases of this kind should be prevented. 



The main point to which I wish to call at- 

 tention, however, is not what to do in past 

 cases of the kind considered, but what to do 

 in order to prevent their occurrence in the 



^ I have since learned that my species was the 

 type species of Pachycrepoideus. This does not 

 alter the case. 



future. In this matter, we must leave the 

 past behind us and build for the future. 

 Looking ahead, not behind, the whole question 

 of nomenclature turns on a single point, that 

 of identity. If those who come after are to 

 build upon what we are doing in the present, 

 stability in nomenclature will primarily de- 

 pend on the means we leave behind us for the 

 identification of the things we name. Nomen- 

 clature, as we all know, is but the tool, the 

 means to the end of systematic work; the end 

 is fundamentally concerned with identity, 

 identity based on, and dependent upon, 

 definition or description. In the great 

 present-day activity in systematic work, 

 enlightened by past failures and errors, 

 it seems to me to be a deliberate fault for a 

 systematist to cause cases like the kind we- 

 have considered. We must all know that what 

 in the far past was regarded as a genus, to-day 

 has become a family or other higher group, 

 and in all probability what is regarded as a 

 genus to-day, in the future may become a 

 much higher group. We have all learned, ere 

 this, that the greatest causes of error, delay 

 and obstruction to progress in systematic 

 zoology at the present time is the meagerness 

 of definition #r description of genera and 

 species. Of what use is it to us, to the future, 

 to the race at large, to science, for a system- 

 atist, although a recognized authority in the 

 group in which he is working, to describe 

 briefly, unrecognizably, new genera or new 

 species ? Does the fact that we know through 

 his efforts that they exist help any of us, help 

 science? Assuredly not; if the units are not 

 recognizable they are nothing more or less 

 than obstructions. Fifty years hence, the 

 systematists will be considering them under 

 the same general classes of cases that we at the 

 present are considering the poorly described 

 genera and species of fifty or more years ago. 

 Having what will then be considered but one 

 or two very general diagnostic characters upon 

 which to base conclusions, in all probability 

 they will be at an utter loss to know into what 

 families or other groups to place them. Of 

 what possible benefit is it, therefore, to de- 

 scribe these things unless we use in every case 

 all the means at our command to make them 



