Synonymic List of tite Euro2)can Triclioptcrygldiu. 443 



to reconstruct, the nomenclature of the whole family, and my 

 })urpose in the present paper is to consider the alterations 

 ])roj)f'sed by Dr. Flach and to set plainly before entomolo- 

 gists my own views, where they differ from those of Dr. Flach, 

 and, luiving- done this, to leave it in their hands to form an 

 unprejudiced opinion on the comparative merits of the systems 

 in question. 



The changes of nomenclature proposed by Dr. Flach form 

 a leading feature in his essay and require s})ecial notice. The 

 manner in which he has treated the genus PtHium exhibits a 

 characteristic example of his style. He has, in fact, adopted 

 an arrangement suggested long ago by Col. Motschulsky, 

 dividing this very complex genus into many subgenera. 

 The creation of what are termed subgenera has always 

 appeared to me objectionable for many reasons : it is impos- 

 sible to define a subgenus with accuracy sufficient to enable 

 a student to determine the proper position of any doubtful 

 species ; if this could be done, and the subgenus proved to 

 exhibit unmistakable anatomical characters, it would become 

 a true genus, and must be designated as such in any subse- 

 quent work. Col. Motschulsky's separation of FtineUa from 

 Fiilium is a clear proof of the truth of what I have said, for 

 no one since his time has ever thought of reuniting those two 

 genera. If it had been possible I would willingly have retained 

 Micrella, Oliyella, and other genera which he proposed at 

 the same time as PtineUa ; but I could find in these no true 

 persistent generic characters ; the differences which they 

 exhibit are merely specific, e.g. the short transversely -jointed 

 antennas of P. Kunzei merge gradually through other species 

 whose thorax is equally devoid of channels into the long 

 slender-jointed antennae of P. exaratum^ and the same may 

 be said of their superficial sculpture and other differences. I 

 found therefore that generic separation could not be sup- 

 ported by anatomical evidence, and was content to retain in 

 the old genus the greater part of its former species, distin- 

 guishing its various divisions by sculptural characters alone 

 — thus avoiding the confusion of a multiplicity of indefinite 

 generic terms. But even if subgeneric names should be 

 deemed advisable, I consider it unjust as well as uncourteous 

 to appropriate to your own credit names previously published 

 by another author, although they be but imperfectly charac- 

 terized. Be this as it may (tor genera are at the best mere 

 arbitrary divisions, depending on the peculiar ideas of indi- 

 vidual authors), in dealing with species greater caution is 

 required. The characters which distinguish species are 

 mainly suiierfieial : anatomical variation, though often useful, 



