THE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
No. 104. SEPTEMBER 1845. 
XIV.—On the Anatomy of Acteeon, with remarks on the Order 
Phlebenterata of M. de Quatrefages. By Guo. J. ALLMAN, 
. M.B., F.R.C.S., M.R.L.A., Professor of Botany in Trinity Col- 
lege, Dublin, late Demonstrator of Anatomy T.C.D.* 
[ With three Plates.] 
In the seventh volume of the ‘ Linnzan Transactions’ is a memoir 
by Colonel Montagu, in which is described, under the name of 
Aplysia viridis, a small gasteropod discovered by this naturalist on 
the coast of Devonshire. The Aplysia viridis of Montagu was 
afterwards separated by Oken from the true Aplysias, and made to 
constitute a distinct genus under the name of Acton. A mollusk 
evidently referable to the same genus is named Aplysiopterus 
neapolitanus by Delle Chiaje, who describes and figures it in his 
great work on the Invertebrate animals of the kingdom of 
Naples. ‘The Itahan naturalist gives some details of its anatomy, 
but his account is manifestly full of errors, and he seems to 
mistake the ramified apparatus in connexion with the stomach 
for a vascular system. A mollusk also apparently referable to 
Oken’s genus Actgon is described in the ‘ Faune d’Europe Sep- 
tentrionale’ of Risso, under the name of E/ysia timida ; and more 
recently M. de Quatrefages (Ann. des Sci. Nat. March 1844) has 
published a very elaborate description of the genus, in which he 
advances some new and startling views to which he had been pre- 
viously led by the examination of Holidina, a small nudibranch, 
apparently an Holis, but for the reception of which this naturalist 
believes it necessary to construct a new genus. The claims of 
M. de Quatrefages’ opinions to reception by naturalists will be 
considered in the present paper. 
The followmg anatomical details have been drawn up from 
careful dissections of Acteon viridis, and as no figure which we 
have seen represents with sufficient accuracy the external cha- 
racters of this little mollusk, we have thought it necessary to give 
among the illustrations of the present memoir a drawing made 
with great care from the living animal. 
* Read before the Meeting of the British Association at aos Sept. 1844, 
Ann. & Mag. N. Hist. Vol. xvi. 
