Mollusca of Great Britain. 367 
their organs of respiration they must rank with the ter- 
restrial Mollusca, are strictly amphibious, living in the 
clefts of rocks and the under surfaces of stones which are 
exposed only by the recess of the tide. "Their food (at least 
that of the A.denticulata, the only one of which I have 
observed the animal,) consists of decaying animal and ve- 
getable substances. It is curious to observe the strange 
confusion that has taken place among later authors as to 
the real habitat of this class. Montagu and Draparnaud 
respectively assigned to their Voluta denticulata and Auricula 
myosotis a place among the marine and terrestrial Mollusca : 
the one from having observed the shells with their animals 
on Alge at high-water mark on the Plymouth coast; and 
the other on dead and decaying wood on the shores of the 
Mediterranean. Baron Férussac indeed was perfectly 
aware of their peculiar organization, but errs in saying 
that they have the power of going out of the water. The 
last-mentioned author has arranged them under his GeAy- 
drophiles, a very interesting sub-order of the pulmoniferous 
Mollusca, but a much too extensive one, since it embraces 
. the Voluta tornatilis, Turbo unidentatus, plicatus, $c. of Mon- 
tagu; all which, from opportunities I have had of examining 
their animals, I am perfectly assured do not agree with the 
present division, having a very different respiratory system 
and a truly marine habitat. 
The want of the internal spiral septa of the shells first 
noticed by Montagu i is rers curious. — $n pe 
E DENTICULATA. a eps 
Animal griseo-purpurascens. Tentacula brevia, annulata. 
Proboscis elongatus. 
Testa oblonga, subventricosa, fragilis, glabra, purpureo- 
VOL. XVI. 3B fuscescens. 
