M. A. de Quatrefages on the Classification of the Annelides. 118 
self to an appeal for the indulgence of those of my brother natu- 
ralists who have essayed the difficult task of coordinating in a 
general work that immense mass of frequently very heteroge- 
neous materials which results from the isolated labour of a great 
number of naturalists. 
7. The observations addressed to me in a letter by M. Clapa- 
rede, and a rapid examination of his ‘Glanures,’ had already called 
my attention to the family of the Capitellacea. The new facts 
which I thus learnt, and especially the positive confirmation of 
the position and nature of the branchiz, the absence of blood- 
vessels, &c., lead me to remove the Dasybranchi from the family 
Arenicolea, and to accept their collocation with the Capitelle and 
Notomasti. But can the family Capitellacea be at once placed in 
the systematic framework of the class? Can we understand its 
affinities? M. Claparéde tells us nothing on this subject; and, 
for my part, I do not believe we can. I shall therefore leave 
this smgular family among the mcerte sedis; for I cannot yet 
form a distinct idea of its relations with the other groups, which 
is perhaps due to my not having myself studied any of its repre- 
sentatives. 
8. The family Sylidea has really engaged much of my atten- 
tion, as M. Claparede supposes. But during my visits to the 
sea-shore, I had scarcely ever looked at it from the point of view 
of a classification of the species. I merely studied in detail cer- 
tain types, especially from an anatomical point of view. The 
proof of this will, I hope, be found in my book. When I had 
to seek to unite all the species described by different authors, I 
found a great difficulty, which will be understood by every one 
who has attempted to do the same. The generic denominations, 
here more than elsewhere perhaps, were not founded upon any 
uniform rule; the nature and the value of the characters adopted 
presented nothing fixed. I have sought to introduce as much 
precision as possible into their appreciation, and it is true that I 
have taken much trouble to find a method which enables the 
genera and species to be characterized without much trouble. I. 
thought I had succeeded by distinguishing, as far as it could be 
done, the tentacles from the antenne and tentacular cirri, three 
sorts of appendages which have been habitually confounded, and 
then by ascribing a generic value to the number of these differ- 
ent appendages. The modifications of the foot have likewise 
furnished me with characters of the first importance. By thus 
adding fresh data to those already employed by my predecessors, 
I believe I have succeeded in preparing a very natural series, in 
which the new species may take their places without violence. 
The essays which I have had to make since the period (already 
distant) when this table was first prepared by me authorize me, 
Ann. & Mag. N. Hist. Ser. 3. Vol. xvii. 8 
