Iii some cases the area is surrounded by a concentric row of 

 approximating heads or dots or of abbreviated lines. These 



collectively constitute the "circlet.'' 



All other terms employed explain themselves. Further on 

 I have enumerated about 80 forms of the genus Campy/odiscus, 

 which I consider as really distinct. The total number of names 

 in the authors amounts to no less than 220 (see the Synonymic 

 ( 'atalogue) ; but synonyms, varieties, nomina nudce, and unde- 

 terminable forms resting on absence of figures and insufficient 

 descriptions have led me to reduce the number to the 80 above 

 mentioned, which include 23 new ones. It is thus seen that I 

 have done away with 197 names of previous authors and re- 

 tained only 57 of them. Some diatomists will, I fear, accuse 

 me of the wholesale "massacre of the innocents,' 7 while others 

 will take me to task for creating too many new "species''! I 

 have done my best not to run into extremes, and have acted 

 with due consideration before eliminating anything, and then 

 only after repeated examination of hundreds of types. I hope 

 I may be forgiven by some of my friends for having taken the 

 great liberty of " doing away '' with some of their " offspring " ! 

 My conviction as to the "non-existence" of species, in the 

 generally accepted meaning of that term, must be my excuse 

 for the reduction of the number of " so-called " species created 

 by divers authors. It follows, according to my mode of reason- 

 ing, that if the species does not exist in nature, no genuine specific 

 characters can be claimed for it. I admit, however, the existence 

 of numerous transient forms of life at the present time, and also 

 that these forms may often be distinguished, and should have 

 names given to them when differentiated by clear and readily- 

 made-out characters ; not by subtle, vague, obsolete distinctions, 

 as is too often the case, which as a rule are proper to individuals 

 only, the offspring of a single parent. Groups of forms may 

 without inconvenience be called Genera for the purposes of 

 memotechny, but not because of their existence in Nature, 

 which does not admit them any more than that of the con- 

 tained " so-called " species. 



