786 CLASS XIII. 
received by us in the first edition of this Handbook, 1. bl. 89. We 
see that in this we have been anticipated by Gray and RaEEve. 
Umbrella Lam. (Gastroplax BLAINY.). 
Pleurobranchus Cuv. Body with flat abdomen, a furrow be- 
tween the mantle and abdomen receiving the branchiz on the right 
side. Mantle covering the whole of back. Velum in front of 
mouth acuminate on each side. ‘T'wo tubular tentacles fissured by 
an external furrow. Vent behind branchia in right side. Shell 
dorsal, contained in mantle, horny or calcareous. 
Comp. on this genus Cuvier Ann. du Mus. v. p. 266 and foll. Pl. Vit. 
Mollusq., Mém. Vit. 
Sp. Plewrobr. Peronii Cuv., 1.1. figs. 1, 2, R. Ant., éd. ill., Moll. Pl. 32, 
fig. 1; from the Indian Sea ;—Pleurobr. Forskalit Lrucx., Fors. Icon. 
Rer. natural. Tab. 28, fig. A, Lepus marinus RUEPPELL, Atlas 1. 1. Tab. 5, 
fig. 2; in the Red Sea;—Pleur. testudinarius Cantr., Plewr. Forskalit 
DeEtLeE Cutase, Memorie, Pl. 41, fig. 11; from the Mediter. &c. Comp. 
CantTRAINE Malac. méd. pp. 87—90. 
Pleurobranchea MEcK., Pleurobranchidium BuAiny. Four ten- 
taculiform laciniz, not retractile. Vent above branchia in the 
right side. Shell none. Mantle shorter than body. 
Sp. Plewrobranchea Meckelii Cuv., DELLE CHIAJE Memorie, Pl. 40, fig. 11, 
CANTRAINE 1.1. Pl. 11. fig. 3; from the Mediterr. Sea, Comp.8. F. LEvE 
Diss. de Plewrobranchea. Hale, 1813, 0. fig. 
Aplysia L., GMEL. (Laplysia L., typogr. error, LAm.). Body 
oblong, limaciform, mostly margined by a broad velum reflected 
over the back. ‘Two contractile tentacles, conical, sulcated, in the 
upper part of head; two productions of the velum surrounding the 
mouth, forming as it were a second pair of inferior tentacles. Hyes 
sessile in front of base of superior tentacles. Branchiz dorsal, 
covered by a production of mantle, with an operculum including a 
flat membranoso-corneous or calcareous shell. 
Comp. SANDER Rane Hist. nat. des Aplysies. Paris, 1828, fol. 
Dolabella Lam. Operculum of branchie towards the posterior 
part of back, including a calcareous shell. Body mostly truncated 
posteriorly with an orbicular declining area. 
Sp. Aplysia Rumphit Rane, Dolabella Rumphii Cuv., Rumen. Amb. Rari- 
teitk. Tab. X. fig. 5 (Tab. xu, fig. N the shell); Cuv. Ann. du Mus. V. p. 
437 and foll., Pl. 30, figs. 1—4, Moll., Mém. 12, Rane 1.1. Pl. 1. 
