114 M.A. de Quatrefages on the Classification of the Annelides. 
I think, to adhere to my opinion. It is, however, very natural 
that M. Claparéde should prefer the classification which he has 
published in his ‘Glanures.?,_ When one has dwelt for a certain 
time upon a collection of ideas, such as that which is summarized 
in a classification, it is very difficult to substitute another sud- 
denly for it. I cannot but be in this position myself; and our 
confréres alone can judge between us. 
It is certain that M. Claparéde and myself have been guided 
by very different considerations in the establishment of our 
genera. I have generally confined myself to the employment, for 
their characterization, of considerations derived from the external 
forms. The only exception that I have made has been the ar- 
mature of the gizzard, to which | shall return presently. 
M. Claparéde, on the contrary, has had recourse to various 
anatomical considerations, such as the length of the trunk, the 
absence or presence of the glands which I have called salivary 
glands, the armature of the pharynx, &c. He has even character- 
ized his genera by the mode of reproduction—that is to say, by 
essentially temporary physiological phenomena, which are con- 
sequently impossible to ascertain at certain seasons of the year. 
I see serious inconveniences in this course. 
On the other hand, my honourable critic seems to me to have 
sometimes given too much importance to certain details in con- 
sidermg them generic characters. Thus, in his opinion, the 
mode of union of the frontal lobes is a generic character. It 
seems to me to be only specific. I shall say as much, and with 
still more reason, of the following character ascribed to his genus 
Pterosyllis :—(char. emend.) “Ventral cirri pimniform, except 
those of the penultimate segments, which are moniliform.” For 
my own part, I should not hesitate to arrange in the genus in 
question every Syllidian which had all the other characters of 
Pterosyllis, but of which the penultimate segment had a pinni- 
form ventral segment like the preceding ones. 
I know that criticism is easy ; and moreover, in this case, I am 
judge in my own cause. I would not, therefore, dwell too parti- 
cularly upon the present question. Nevetheless I believe I may 
indicate that my table gives prominence to a certain number of 
general results which do not appear to me to follow so clearly 
from M. Claparéde’s table. I think, moreover, that I can ad- 
duce a consideration which, I believe, would have been decisive 
for any naturalist placed in my position. 
M. Claparéde in arranging his table has given his particular 
attention to the species which he knew thoroughly from having 
well studied them. For my part, J had to take into account all 
the species described by my various confréres, past or present. 
Now a very great number of these are known to us only by 
