CLASS PTEROPODA. 19 
It appears that we must likewise place here, 
The CyMBULIA of Péron, 
Which have a cartilaginous or gelatinous envelope, in the form 
of a boat, or rather of a hoof, bristling with some little points 
in longitudinal series. ‘The animal has two great wings, with 
a vascular tissue, answering as both gills and fins, and be- 
tween them, on the open side, a third smaller lobe, with three 
points. The mouth, with two small tentacula, is between the 
wings, towards the closed side of the shell, and above, two 
small eyes, and the orifice of generation, from which issues a 
penis, in the form of a small proboscis. From their trans- 
parency, the heart, brain, and viscera, can be distinguished 
through the integuments. 
PNEUMODERMON, Cuv., 
Begins to be somewhat removed from Clio: the body is oval, 
without mantle, and without shells, the gills attached to the 
surface, and formed of small leaflets, ranged in two or three 
lines, disposed like an H on the side opposite to the head. 
The fins are small; the mouth, furnished with two small lips 
and two bundles of numerous tentacula, terminated each by a 
sucker, has a small lobe or fleshy tentaculum underneath. 
The known species (Prewmodermon Peronii, Cuv., Ann. 
du Mus. IV. pl. lix., and Péron, ib. XV. pl. ii.), has been taken 
in the ocean by Péron. It is scarcely more than an inch long. 
LIMACINA, Cuv., 
Should, according to the description of Fabricius, have close 
relations with pneumodermon ; but their body is terminated 
by a spiral tail, and is lodged in a very thin shell, of one whorl 
and a half, umbilicated on one side, and flatted at the other. 
The animal makes use of its shell as a boat, and of its wings 
as Oars, when it wishes to swim at the surface of the water. 
G2 
