38 CLASS GASTEROPODA. 
claviform tentacula, similar to those in doris, are four, and 
sometimes six others, simply pointed. (Doris quadrilineata, 
Miill., &c.) 
TRITONIA, Cuv. 
The body, superior tentacula, and genital organs, as in doris; 
but the anus, and orifice through which the peculiar liquid 
is secreted, are on the right, behind the organs of generation. 
The gills, which resemble little trees, are arranged along the 
sides of the back ; and the mouth, provided with broad mem- 
branous lips, is armed inside with two horny and trenchant. 
lateral jaws, which may be compared to a pair of sheep-shears. 
Trit. Hombergii, Cuv. Ann. du Mus. I. xxxi. 1,2; a large 
species, of a copper colour, from the coast of France. 
The same locality produces many others, which vary greatly 
in size and the form of their gills. Several of them are very 
small. (TZrit. elegans, Trit: rubra, Trit. glauca, &c.) 
THETHYS, Lin. 
Two rows of gills, resembling branching tufts, along the 
back, and a very large, membranous, and fringed veil, upon 
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 the margin of 
which projects a small conical point. The orifices of the 
genital organs, of the anus, and of the peculiar fluid, are 
situated as in the tritoniz; the stomach is membranous, and 
the intestine very short. 
T. fimbria, L., Cuv. Ann. du Mus. XII. xxiv.: grey, 
spotted with white. A beautiful species, from the Mediter- 
ranean. 
ScYLLEA, Lin. 
Body compressed; the foot narrow, and marked with a 
