110 M.A. de Quatrefages on the Classification of the Annelides. 
than that of the other Vermes. Apart from the question of 
moneeciousness or diceciousness, the Hirudinea must, in any case, 
it appears to me, form a distinct class. 
I have discussed in haste, but at some length, this portion of 
M. Claparéde’s article, because it relates to a general question. 
I shall be very brief upon some points of detail, to which, how- 
ever, I think it necessary to reply. Being pressed for time, | 
ask permission to examine them in the same order in which the 
author has presented his remarks. 
1. M. Claparéde rather severely criticises the manner in which 
I have regarded the relations existing between the genera Nerine, 
Leucodore, Polydore, and Spio. As regards the last, there will 
be found in my book a short discussion, giving the reasons for 
its place among the incerte sedis. The second and third, which 
M. Claparéde declares only form one genus; are certainly very 
distinct. The table itself indicates a character which appears to me 
to be very prominent, and which is in accordance with others. 
As to the approximation of Nerine and Leucodore, it is abso- 
lutely impossible for me to accept it. I have studied these two 
types in the living state, and they are completely different. The 
law of repetition of segments is very exactly observed in all the 
Nerinea; it is very little followed in the Leucodorea. By itself 
this character justifies, in my eyes, the position which I have 
assigned to the two groups. There are plenty of other differ- 
ences which I cannot detail here; but this, it appears to me, 
suffices in any case to prevent the union of two such different 
types in the same family. Notwithstanding the high authority 
of Sars, I shall therefore persist in my opinion, and must beg 
my confréres to delay their judgment until they have before them 
the necessary evidence—that is to say, my book and my plates. 
2. Contrary to the opinion of M. Claparéde, the Aonides, 
which I have been able to observe in the living and perfect state 
since the publication of my first note upon them, in the ‘ Magasin 
de Zoologie,’ 1843, are very distinct from Nerine, although 
furnished with the large tentacles which appear to characterize 
the family, and which alone may perhaps give them some resem- 
blance to the Leucodorea. 
3. I agree with M. Claparéde in the objections which might 
be raised against the place which I assign to Tomopteris, and I 
have taken care to state this im my text. This position is pro- 
bably only provisional ; but in the present state of science I do 
not very well know where we can place these species, belonging 
to a type in the highest degree aberrant. Moreover, M. Clapa- 
réde in criticising my opinion, has not made known his own. 
4. M. Claparéde attributes my uncertainty, and the course 
that I have frequently taken of putting a certain number of 
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