166 MOLLUSCA. 
tre. The mouth is situate underneath the tentacula. It 
consists of a large funnel, covered within with soft papillee, 
destitute of jaws or tongue. The gullet is short, the sto- 
mach simple, fleshy, and covered with a thick cuticle. The 
salivary glands are slender and branched, and open into the 
gullet. The intestine is likewise short, and proceeds di- 
rectly to the anus. The liver pours the bile into the canal 
at the pylorus; and likewise sends out another duct, which 
opens externally near the anus. The organs of generation 
are similar to the Doris. The 7. fimbria is the type of the 
genus, a figure of which, with its anatomical details, is given 
by M. Cuvier, in his Mémoire sur le Genre Thetys. 
Genus VatvatTa.—lIn this genus are included several 
species which resemble in aspect the aquatic pulmoniferous 
gasteropoda. The branchiz appear in the form of a fea- 
ther, with a central stem, and a row of compound branches 
on each side, decreasing in size from the base to the free 
extremity. This stem issues from the neck near the middle, 
a short way behind the anterior tentacula. Near this plume, 
ut towards the right side, is a single simple filament, like 
a tentaculum. The anterior tentacula occupy the usual 
position, are setaceous, and have the eyes placed at the base 
behind. The spiral shell is capable of containing the body, 
and the aperture can be closed by a spirally striated oper- 
culum attached to the foot. The internal structure is un- 
known. 
Genus PateLta.—Shell entire. Mouth with tentacula. 
This genus differs from the others of the order to which it 
belongs. The back is covered by a conical shell, within 
the cavity of which the animal is capable of withdrawing 
itself. The cloak is large, covering both the head and foot. 
It is united with the shell along its superior margin. The 
