M. A. de Quatrefages on the Classification of the Annclides. 117 
species in another family. The example cited by the Genevese 
savant, that of Tetraglene and Pseudosyllis, is due to a misun- 
derstanding easy to explain. 
Grube had described in the same work, and figured on the 
same plate, the asexual and sexual forms of a Syllidean. To 
the former he gave the name of Pseudosyllis, to the second that 
of Tetraglene. Ehlers, justly uniting the two forms under a 
common name, chose the expression Tetraglene. I have acted 
like him. The name Pseudosyllis consequently remained wnem- 
ployed, and, as I thought it a very good one, I applied it to a 
small genus, not indeed of Syllidea, but of Hestonea. 
This is what has caused a misunderstanding between M. Cla- 
paréde and myself, for which my honourable confrére has already 
testified his regret. Perhaps I might be reproached for having 
adopted a name proposed by another author, giving it a new 
signification. If this is an error, I have fallen into it more than 
once in my book. He who passes in review the whole of a tota- 
lity of works frequently has, by this means, data which were 
wanting to the authors of isolated researches ; he looks at many 
questions from a different point of view. The characterization, 
the limitation, and the distribution of genera sometimes seem 
to him to require some modifications. Shall he therefore pro- 
ceed to abolish the names proposed by his, fellow labourers? — I 
have not thought it necessary to act thus. As far as possible, 
I have retained the old denominations, and I have avoided intre- 
ducing new ones. A few words of explanation suffice in such 
cases to prevent confusion. In the present case mistake was 
less to be dreaded, it scems to me, as two different families were 
in question, and, apart from all other indications, the bzramose 
feet and the number of e7ght antenne indicated in the table would 
forbid any one to suppose that I meant to speak of Pseudosylls, 
Grube, which has the feet uniramose and only three antenne 
on the head. 
13. M. Claparéde calls attention to the fact that the genus 
Heterosyllis figures twice in wy table. To complete his obser- 
vation, he might have added that the genus Pterosyllis is not 
named. ‘This is the double result of a printer’s error, which I 
should have avoided by correcting my proofs better, but which, 
fortunately, does not recur in the table forming part of my 
book. 
14. The observations of M. Claparéde relate principally to 
the Annelides; he says but little of my table of the Gephyrea, 
and confines himself to the assertion of an opinion which is not 
well founded. I thought it right to suppress as a genus the 
group Phascolosoma, as to the characters of which authors did 
not seem to me to be agreed (see, among others, the works of 
