MOLLUSCA. 787 
Aplysia wuctor. Body elongate, not truncated posteriorly, angus- 
tate. Dorsal operculum of branchie including a membranous horny 
shell. 
Comp. Bonapsou De quibusd. animalib. marinis, pp. 1—53, Tab. 1.—1v. 
Cuvier Ann. du Mus, 11. pp. 287—314, Pl. 11. Mollusg., Mém. 1x.; DELLE 
Cu1asE Memorie, 1. pp. 25—76, Tab. 11.—v. 
These animals, on a first impression, resemble gigantic slugs (Limaces). 
The ear-shaped tentacles have given occasion to stamp this genus with the 
name of Sea-hare (Lepus marinus). They live on fuci; and shed a purple 
fluid at the margin of the mantle. 
Sp. Aplysia depilans L., Bowapson 1.1. Tab. 1.—1v. Rane 1. 1. Pl. 16, 
Cuvier R, Ant., éd. ill., Moll. Pl. 33; one of the largest species; of this 
Mediterranean species, under the name of Lernwa, BoHADSCH gave l. cit. 
a detailed description and a masterly anatomical investigation. In that 
and in other seas still different species of this genus are found. The eggs 
are laid in long tortuous strings. The development of Aplysia has been 
observed by VAN BENEDEN, Ann. des Sc. nat. 2e Série, XV. pp. 123—128, 
Pl, i. 
Notarchus Cuv. 
Bursatella BLAINV. 
Note.—Rane 1. |. concludes that these genera form sections only of the 
great genus Aplysia. Of Notarchus the same has been noted by the cele- 
brated voyagers Quoy and GaimarD, Voyage de l’Astrolabe, Zoologie, 11. 
pa Zhe 
Gastropteron Mrck. ‘Tentacles none. Margins of foot ex- 
panded into ample wings. Shell none. Branchie pectinate, 
almost entirely naked; a small duplicature of mantle, produced 
beyond the body into a filiform lacinia. 
Sp. Gastropteron Meckelii J. F. J. Kosse, Diss, de Pteropodum ordine et 
novo tpsius genere, Hale, 1813, 4to, figs. 11—18, Clio Amati DELLE CHIAJE, 
Memorie, pp. 53—59, Tab. 1. figs. 1—8; CANTRAINE 1. 1. Pl. 4, fig. 4; a 
small mollusc from the Medit. Sea, of a rose-red colour; the only species 
hitherto known. 
Acera MUELLER (in part), Lam. (Doridium Mercx., Lobaria 
Buarny.). Tentacles none. Veil of head large, separated from 
mantle by a transverse furrow. Vent, orifice of generation, bran- 
chize and heart placed at the right side; branchie posterior. A 
small shell included in the posterior part of mantle, flat, calcareous 
at the incurved apex, elsewhere membranous, thin. 
Comp. on this and the two following genera Cuvier Ann. du Mus. xvr. 
pp. 1—18, Mollusg., Mém. x. 
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