352 SUPPLEMENT 
figure approaches to that of the slugs. Its colour is a reddish 
brown; it has four horns in the head; and the eyes, which are 
very small, are situated between the two hinder ones. 
This aplysia has a reservoir of ink like the sepia, and em- 
ploys it for the same purpose, that is, it ejects it for the pur- 
pose of escaping the pursuit of its enemies. It inhabits, in 
preference, the muddy bottom of the water, and lives on small 
crabs, small mollusca, &c. 
Draparnaud thinks we should not regard the two anterior 
prolongations of the head as tentacula or horns; if such then 
be the case, this genus in reality will have but two. 
The remarkable molluscous animal, called OMBRELLA by 
Lamarck, and Gastroplax by de Blainville, exhibits many 
relations in its interior structure with aplysia. We know 
nothing respecting the manners of this animal, which lives 
in the Chinese seas. It is sometimes called the Chinese 
parasol. From the extremely anomalous position of the 
shell, it is not easy to conceive how it can crawl. Accord- 
ingly, M. de Blainville, considering that the back covered 
with a skin extremely thin, has need of being sheltered from 
the action of external bodies, has supposed that this mol- 
luscum was, as it were, compressed between two protecting 
bodies, one inferior, or the shell, and the other superior, 
which might be a sort of valve, extremely thin, and adherent, 
like the anomia, or even some rock. An hypothesis which 
may be yet further supported by a consideration of the cavity, 
at the bottom of which is the mouth, and towards which the 
pedicled tentacula might, by their movement, determine the 
arrival of nutritive substances. 
In the order of HETEROPODA, we must pass the first two 
genera, and come to the FIROLZ, of which we can say but 
little. Their manners and habits are but little known. They 
are found, as it would seem, pretty commonly in all the seas 
of warm regions, and even in the Mediterranean, where they 
ee 
