THE ANNALS AXD MAGAZINE OF NATURAL HISTORY, No. 104. SEPTEMBER 1845. XIV. — On the Anatomy of Actseon^ with remarks on the Order Phlebenterata of M. tie Quatrefayes. Bv Geo. J. Allmax, . M.B., F.R.C.S., M.R.I.A., Professor of Botany in Trinity Col-lege, Dublin, late Demonstrator of Anatomy T.C.D.* [With three Tlates.] In the seventh volume of the ' Linncean Transactions ^ is a memoir by Colonel Montagu, in which is described, under the name of Aplijsia viridis, a small gasteropod discovered by this naturalist on the coast of Devonshire. The Aphjsia viridis of Montagu was afterwards separated by Oken from the true Aplysias, and made to constitute a distinct genus under the name of Actceon. A mollusk evidently I'eferable to the same genus is named Aplysiopterus neapolitanus by Delle Chiaje, who describes and figm'es it in his gi-eat work on the Invertebrate animals of the kingdom of Naples. The Italian naturalist gives some details of its anatomy, but his account is manifestly fidl of errors, and he seems to mistake the ramiiied apparatus in connexion with the stomach for a vascular system. A molhisk also apparently referable to Oken's genus Actaon is descril^ed in the ' Faune cVEurope Sep-tentrionale ' of Risso, under the name of Elysia timida ; and more recently M. de Quatrefages (Aim. des Sci. Nat. ]\larch 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 Eolidina, a small nudibranch, apparently an Eolis, 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 following anatomical details have been drawn up from careful dissections of Actceon viridis, and as no figm-e which we have seen represents with sufficient accm-acy 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 York, Sept, 1844. Ann. ^ Mag, N, Hist, Fb/.xvi. M
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