GASTEROPODA NUDIBUANCHI ATA. 24t'3 



danger ; anterior to the clavifonn tentacula, similar to those in Doris, are four, 

 and sometimes six others, simply pointed. 



TRITONIA, Cuvier. . 



The body and superior tentacula, as in Doris ; but the orifices through 

 which the peculiar liquid is excreted, are on the right : the branchiae, which 

 resemble little trees, are arranged along the sides of the back ; and the mouth, 

 provided with broad membranous lips, is armed inside with two horny and 

 trenchant lateral jaws, which may E>e compared to a pair of sheep-shears. 



THKTHYS, LinncBus. 



Two rows of branchiae resembling branching tufts along the back, and a very 

 large membranous and fringed veil on the head, which shortens as it curves 

 under the mouth ; this latter is a membranous proboscis without jaws ; on the 

 base of the veil are two compressed tentacula, from whose margin projects a 

 small conical point. 



T. Jimbria, Lin. Grey, spotted with white ; a beautiful species from the 

 Mediterranean. 



ScYLLjEA, Linn&us. 



Body compressed ; the foot narrow and marked with a furrow, which enables 

 it to clasp the stems of the fuci ; no veil ; the mouth resembling a little pro- 

 boscis; orifices as in Thethys; the compressed tentacula terminated by a 

 cavity, from which issues a little uneven point, and two pairs of membranous 

 crests on the back, the internal 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, Lin. Common on all the floating fucus of almost every sea. 



GLAUCUS, Forsier. 



Body elongated ; having four very small conical tentacula, and on each 

 side three branchiae, each of which are formed 

 of long slips arranged like the sticks of a fan, 

 which also aid them in swimming. They are 

 beautiful little animals that inhabit the Medi- 

 terranean and the Atlantic, prettily coloured 

 with blue and nacre ; they swim on their back 

 with great swiftness- Their anatomical struc- 

 ture is very similar to that of the Tritonia, 

 but the species are not well ascertained. The 

 remaining genera are the Laniogerus, Blain- 

 ville, which have the body shorter and thicker than the glaucus, but with four 

 similar tentacula; the Eolidia, Cuvier, which resemble small limax informis; 

 the Carolina, Brugueir, with retiform branchiae arranged in transverse rows 



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