40 CLASS GASTEROPODA. 
CAVOLINA, Brug. 
The tentacula of the eolidia, with retiform gills, ar- 
ranged in transverse rows on the back. (Doris peregrina, 
Gm., &c.) 
N.B. This genus must not be confounded with the cavolina 
of Abildgaard, which is the hyalea. 
FLABELLINA, Cuv. 
The tentacula of the eolidiz, with radiating retiform gills, 
supported by five or six pedicles on each side. They are 
closely related to the glauci; and, in fact, all the nudi- 
branchiata, whose gills are situated on the sides of the back, 
are nearly allied. (Doris affinis, Gm., Cavol., Polyp., Mar. 
vii. 4.) 
TERGIPES, Cuv. 
The form of the eolidia, but only two tentacula, with a 
range of cylindrical gills on both sides of the back, each of 
which is terminated by a little sucker or cup, and which are 
used by the animal as feet to walk upon its back. ‘The 
species known are very small. (Limax tergipes, Forskal, &c.) 
BusIris, Risso, 
The body oblong, and back convex ; two filiform tentacula, 
and behind them, on the nape, two plumiform gills. (Busi- 
ris griseus, Risso.) 
PLACOBRANCHUS, Van Hasselt. 
Two tentacula, and as many labial lobes. The whole back, 
widened by its margin, is covered with numerous radiating 
striez, which are the gills. In its ordinary condition the 
widened borders of the mantle are turned up, and cross each 
