GASTEROPODA TKCTIBR ANCHIATA. 
45 
are attached along the right side in the furrow, between tlie mantle 
and the foot, forming a series of pyramids divided into triangular 
laminulae. The mouth in the form of a small proboscis, is sur- 
mounted by an emarginated lip, and by two tubular and cleft 
tentacula ; the genital orifices are before, and the anus behind the 
branchiae. There are four stomachs, the second of which is fleshy 
and sometimes armed with bony appendages, and the third, furnished 
internally with salient longitudinal laminae ; the intestine is short. 
Various species inhabit both the Mediterranean and the At- 
lantic, some of which are large and marked with the most 
beautiful colours*. 
Pleurobranch-ea, Meckel. — PleurobrxVnchidium, Bl. 
Have the branchiae and genital orifices situated as in Pleurohranchus ; 
but the anus is above the branchiae, the margins of the mantle and 
foot project but little, and on the fore-part of the former are four 
short, distant tentacula, forming a square, which reminds the observer 
of the anterior disk of the Acerae. I can find but one stomach, which 
is merely a dilatation of the canal, with thin parietes. A multifidous 
glandular organ opens behind the genital orifices ; there is no vestige 
of a shell. 
Pleurob. Meckelii, Leve, Diss.de Pleur., iSlSf. The only 
species knoAvn; from the Mediterranean. 
Aplysia, Lin.X. 
Have the margins of the foot turned up into flexible crests, sur- 
rounding the back in all its jjarts, and even susceptible of being 
reflected over it ; the head supported by a neck more or less long ; 
two superior tentacula excavated like the ears of a quadruped, with 
two flattened ones on the edge of the lower lip ; the eyes above the 
former. The branchiae are on the back, and consists of highly com- 
plicated leaflets attached to a broad membranous pedicle, covered by 
a small mantle also membranous, in the thickness of which is a flat 
* Pleurohranchus Peronii, Cuv., Ann. dn Mus., V, xviii 1,2; — PI. tubercu- 
latus, Meckel., Anat. Coinpar., 1, v, .S3 — 40; and some new species, such as 
the Pleur. ohlongus, Descr. de I’Eg., Moll. Gaster., pi. iii, f. 1 ; — Plaur auranfiacus, 
Id., Risso., Hist. Nat. Merid. IV, pi. i, f. 8 ; — PI. luniceps, Cixv. ; — PL Forskalii, 
Forsk., pi. xxviii, and Leuckard, App., Ruppel., An. Invert., pi. v; — PI. ciirinus, 
Ib., f. 1. 
The genus Lamellaria, Montag., Lin. Trans., XI, pi. xii, f. 3 and 4, does not 
appear to me to differ in any essential point from Pleurohranchus ; the same obser- 
vation applies to the Berthella of Blainv., Malac., pi. -\liii, f. 1. The latter is 
distinguished merely because the mantle is not emarginated above the head, as is 
the case in many species of Pleurohranchus. The PI. ohlongus would belong to it, 
and even the PI. luniceps. 
-b It is the genus Pleurohranchklium of Blainv., Malac., pi. xliii, f. 3 ; but not as 
he thinks the Pleurohranchus tuherculatus of Meckel. 
J Aplusia, which cannot clean itself, — a name given by Aristotle to certain 
Zoophytes. Linnaeus erroneously applied it as above. The animals here spoken of 
were well known to the ancients, who styled them Sea-Hares, and attributed to 
them many fabulous properties. 
