42 
MOLLUSCA. 
mouth resembling a little proboscis ; orifices as in Thethys ; the com- 
pressed tentacula terminated by a cavity, from which issues a little 
uneven point, and two pairs of membranous crests on the back, the in- 
ternal surface of which is furnished with pencils of filaments, which 
are the branchiae. The middle of the stomach is invested with a 
fleshy ring, internally armed with horny and trenchant laminae, like 
knives. 
S. pelagica, L. ; Cuv., Ann. du Mus., VI, Ixi, 1, 3, 4. Com- 
mon on the floating focus of almost every sea. 
Glaucus, Foj'ster. 
Have the body elongated, and the orifices of the anus and of the 
genital organs as in the preceding ; four very small conical tentacula, 
and on each side three branchiae, each of which is formed of long 
slips arranged like the sticks of a fan, which also aid them in swim- 
ming. They are beautiful little animals, that inhabit the Mediter- 
ranean and the Atlantic, prettily coloured with blue and mother-of- 
pearl ; they swim on their back with great swiftness. Their anato- 
mical structure is very similar to that of the Tritonia, but the species 
are not yet well ascertained*. 
Laniogerus, Blainv. 
Have on each side two series, of small and finely pectinated laminfe, 
which are the branchiae ; the body shorter and thicker than that of a 
Glaucus, but there are four small similar tentacula. f 
Eolidia, Cuv. 
Have the form of a small Limax, with four tentacula above, and two 
on the sides of the mouth ; the branchiae are composed of laminae, ar- 
ranged like scales, more or less croAvded, on each side of the back. 
Found in every seaj. 
Cavolina, Brug. 
Have the tentacula of the Eolidiae, with radicating retiform branchiae, 
arranged in transverse rows on the back|l. 
* Doris radiata, Gm., Dap., Phil. Trans., LIII, pi. iii ; — ScylUe macrce, Bose., 
Hist, cles Vers ; — Glaucus atlanticus, Blumenh., fig., Nat. Hist., pi. 48, and Manuel., 
fr. trans., TI, p. 22 ; Cuv., Ann. du Mus. VI, Ixi, ii, Pdron, Ann. Mus. XV, 
iii, 9. 
-f- Laniogerus Elforfii, Blainv., Malac, pl. xlvi, f. 4. 
t; Doris papillosa, Zool. Dan., CXLIX, 1 — 4; — Doris hodoensis, Gunner., Act. 
Hafn., X, 170 — Doris minima, Forsk., Ic., xxvi, H ; — Doris fusiculala, Id., Ib., G ; 
— Doris branchialis, Zool. Dan. CXLIX, 5 — 7 ; — Doris cctridea, Lin. Trans., VII, 
vii. 84 ; — Eolidia Mstrix, Otto., Nov. Act. Nat. Cur., IX, xxxviii, 2, &c. 
II Doris peregrina, Gm., Cavolini, Polyp. Mar., VII, 3 ; — Eolidia annulkornis, 
Chamisso, Nov. Act. Nat. Cur., XI, part II, pl. xxiv, f. 1 ; — Doris longicornis, Lin. 
Trans., IX, vii, 114. 
N.B. This genus must not be confounded with the Cavolina of Abildgard, which is 
the Ilyalmt. 
