"42 MOLLUSCA. 



mouth resembling a little proboscis ; orifices as in Thethys ; the com- 

 pressed tentacula terminated by a cavity, from Avhich 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 Avith a 

 fleshy ring, internally armed with horny and trenchant laminee, like 

 knives. 



5. pelagica, L. ; Cuv., Ann. du Mus., VI, Ixi, 1, 3, 4. Com- 

 mon on the floating focus of almost every sea. 



Glaucus, Forster. 



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, Avhich 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 laminae, 

 which are the branchiae ; the body shorter and thicker than that of a 

 Glaucus, but there are four small similar tentacula. f 



EOLIDIA, CilV. 



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 crowded, on each side of the back. 

 Found in eveiy seaj. 



Cavolina, Brug. 



Have the tentacula of the Eolidiae, with radicating retiform branchiae, 

 arranged in transverse rows on the back||. 



* Do)-is radiaia, Gm., Dup., Phil. Trans., LIII, pi. iii ; — Sci/llee macrie, Bosc, 

 Hist, ties Vers ; — Glaucus atlantkus, Blumenb., fig., Nat. Hist., pi. 48, and Manuel., 

 fr. trans., II, p. 22 ; Cuv., Ann. du Mus. VI, Ixi, ii, Peron, Ann. Mus. XV, 

 iii, 9. 



t Laniogerus Elfortii, Blainv., Malac, pi. xlvi, f. 4. 



X Doris papulosa, Zool. Dan., CXLIX, 1 — 4; — Doris hodoensis, Gunner., Act. 

 Hafn., X, 170 — Doris minima, Forsk., Ic., xxvi, H ; — Doris fasiculata, Id., lb., G ; 

 — Doris branchialis, Zool. Dan. CXLIX, 5 — 7 ; — Doris carulea, Lin. Trans., VII, 

 vii. S4 ; — Eolidia hisfrix, Otto., Nov. Act. Nat. Cur., IX, xxxviii, 2, &c. 



II Doris peregrina, Gm., Cavolini, Polyp. Mar., VII, 3 ; — Eolidia annulicornis, 

 Chamisso, Nov. Act. Nat. Cur., XI, part II, pi. xxiv, f. i ; — Doris longicornis, Lin. 

 Trans., IX, vii, 114. 



N.B. This genus must not be confounded with the Cavolina of Abildgard, which is 

 the IJtjalfca. 



