261 
have not used it for anv of the species treated of in my paper. 
Schneider s second reason is due to a misunderstandig, as he 
namely has got the impression, that I regard the operculum of 
S ertularia as an inteinal structure placed under the original roof 
of the hjdiotheca, and he cannot understand such an operculum 1 ), 
in which I quite agree with him. I cannot, however, understand 
in what manner Schneider has got this impression. He declares 2 ) 
that he only knows my investigations from the partial translation 
which has been given by Markthanner-Turneretscher 3 ), 
but in this the position of the operculum in Sertularia is mentioned 
in the following way: „Die Mundung der Hydrothek ist an der 
abcaulinen Seite mit einer tiefen Einbuchtung versehen, in welcher 
das Deckel befestigt ist u , and in my paper I say quite the same 
in Danish as well as in Latin. After having set forth the last 
named objection Schneider says: „Diese Bedenken lassen mich 
vor der Hånd davon absehen, Levinsen’s Gattungskaraktere als 
gute anzuerkennen“ after which he adds: „Damit sei ihnen indessen 
nicht jeder Werth iiberhaupt bestritten.“ Schneider does not 
explain what he means by this sentence, but it seems permissible 
to understand his words as meaning, that the characters named 
may be used as species-characters. 
I think that the chief reason for Schneider’s different 
systematic standpoint from mine must be sought for in our different 
mode of working. While I have endeavoured to divide the genera 
as strictly as possible, deferring the question as to their mutual 
lelation, till a sufficient amount of knowledge has been secured, 
Schneider’s chief aim has been to unite and to find — as fast 
as possible — the unity in the multiplicity. Therefore he does 
not like strictly defined genera which apparently protest against 
this unity, and, besides, he has no time to wait, until the great 
bulk of the hitherto described species have been examined as to 
' „Auf Grund dieser Erwiigungen kann eigentlich von einem inneren 
Deckel nicht geredet werden* (p. 522). 
2 ) 54, p. 511. 
3 ) 37. 
