Prof. E. Claparéde on the Structure of the Annelida. 8389 
order Nereidea) has appeared, has nothing general except its 
title. It contains in reality a series of monographs devoted to 
certain species found in the Adriatic. These monographs are 
combined into a sort of whole by taxonomic considerations. 
There is nothing deserving the name of a ‘ Treatise on Annelida ;’ 
the number of types investigated by the author is too small for 
this. Nevertheless M. Ehlers’s monographs are models of 
exactitude. Whenever I have had the opportunity of repeating 
the observations of this anatomist, I have been obliged to admit 
their perfect truthfulness, even in details of secondary import- 
ance. 
The ‘ Histoire Naturelle des Annelés’ of M. de Quatrefages 
corresponds better with its title. It is a real treatise on the 
Annelida Polycheta. The author has set before him two ob- 
jects :—in the first place, a natural classification founded on ana- 
tomy; and then an enumeration of all names and synonyms, in 
order to enable any one to find more easily the numerous me- 
moirs and passages relating to Annelida which are now-a-days 
disseminated pretty nearly everywhere. The author has devoted 
long-continued attention and assiduous and prolonged labour 
to this rather dry work, the fruits of which will chiefly be 
gathered by others. No ‘doubt this immense compilation pre- 
sents some gaps or omissions, several of which will be indicated 
in the present memoir ; but it could hardly have been otherwise, 
considering the labyrinth through which the author had to find 
his way. The clue which the ‘ Histoire des Annelés’ places in our 
hands will be henceforward a guide which cannot be disdained. 
This guide, indeed, must not be employed without a check. 
The author has often consulted plates without taking the trouble 
to read the corresponding text. The imperfection of a figure, 
or a slip of the graver, has often led him into serious mistakes. 
‘Thus, in his family Nerinea, M. de Quatrefages characterizes the 
worms of the genus Pygospio (Clap.) by the sole circumstance 
of their having uniramous feet, in opposition to all the rest of 
the family, in which the feet are biramous*. It is only neces- 
sary to open the volume in which I established the genus Py- 
gospio + to see that I indicate the feet as biramous, and that I 
describe in detail each ramus and the sete which it bears. M. 
de Quatrefages, neglecting to read the text, has, no doubt esta- 
blished his false diagnosis from a figure on a small scale which 
accompanies my memoir, in which the dorsal ramus covers the 
ventral one, and scarcely allows it to be seen. The following is 
another perfectly similar example. Under the name of Lumbri- 
* Hist. Nat. des Annelés, tome i. p. 437. 
+ Beobacht. tiber Anat. und Bites Ta ea Thiere an der Kuste der 
Normandie angestellt. Leipzig, 1863, p. 37. ane 
