** Note on the Classification of the Annelides.” 105 
syllis) enumerated by the side of genera with the gizzard really 
unarmed (Tetraglene ?) as furnished with an unarmed gizzard, 
have the gizzard really armed. One of them (Autolytus) even 
presents perhaps the most formidable armature to be found 
among the Syllidea. The genus Heterosyllis is enumerated 
twice, first among the Syllidea with the gizzard armed, and then 
among those with an unarmed gizzard. No doubt we may here 
suspect a dapsus calami, which has led in one case to the intro- 
duction of the name Heterosyllis in place of some other. 
But the greatest reproach that can be made against the clas- 
sification of the Syllidea by M. Quatrefages is that of admitting 
a certain number of genera which, in the present state of 
science, must undoubtedly be cancelled. It is well known, and 
M. Quatrefages was one of the first to demonstrate the fact, that 
certain Syllidea present an alternation of generations—that is to 
say, a regular alternation of sexual and asexual generations. 
The asexual generations appear always to have an “armed Ve 
zard*, and the sexual generations an unarmed one ; or rather, to 
speak more accurately, the latter have no gizzard. 
Hence for a long time the sexual generations have been re- 
ferred to other genera than the asexual generations. In the 
list of genera adopted by M. Quatrefages we remark the gencra 
Tetraglene, Ioida, Polybostrichus, Sacconerets, and Dipleceraa 
(perhaps also Macrochata and Polynice), which are formed by 
sexual generations; the others (at least those with which we are 
acquainted) represent asexual generations. The admission of all 
these genera consequently necessitates that a single species may 
be cited under three different names. ‘Thus the asexual form of 
such a species will belong to the genus 4uwtolytus, the male 
sexual form to the genus Polybostrichus, and the female sexual 
form to Sacconereis. If necessary, we might assign to this 
species a fourth place, as the genus Diploceraa of Grube appears 
to be synonymous with Polybostrichus, Hirst. Finally, this in- 
convenience becomes extreme when M. Quatrefages places among 
the Hestonea the genus Pseudosyliis, Grube, consisting of asexual 
worms of which ‘the sexual a7 (the genus Tetraglene, Grube) 
is placed by him in the family Sydlidea. 
* We here borrow the terminology of M. Quatrefages. By many authors 
the name gizzard is used in quite a different sense. It is there applied, 
not to the anterior part of the digestive tube, which is armed with teeth, 
but to the glandular vesicle which follows this. Perhaps, however, the 
inconsistencies in the application of the principle to which we have ¢ ad- 
verted above may be owing to M. Quatrefages considering all those giz 
zards to be unarmed which have not a pair of jaws properly so called. i 
this case he would take no account of the formidable armature of teeth 
which is presented by certain genera, and which furnishes excellent cha- 
racters for classification. 
