ON GASTEROPODA. 3507 
on the ground, or fasten itself thereto, is doubtful. The first 
position does not seem at all probable; but the second is 
more likely to be founded in truth, from the peculiar form of 
the foot, in the style of a sucker. 
The janthine, in all probability, feed upon animal sub- 
stances, though we possess no certain information on this 
subject. Neither are we much better acquainted with their 
mode of propagation. According to Forskal it would appear 
that the female preserves her eggs in a sort of matrix, or in- 
flated portion of the oviduct; at least he has several times 
seen young individuals issue from the body not larger than 
grains of sand, and which in the microscope, have appeared 
to him provided with a shell similar to that of the mother, 
with the exception of colour. According to the same ob- 
server, it would appear that the young animal presents some 
differences more considerable, by having towards the aper- 
ture of the shell two transverse laminz, rounded, and ciliated 
in their circumference, which it might use as fins for loco- 
motion. 
Notwithstanding the probability of what we have just 
advanced respecting the ovo-viviparous character of the 
janthine, Sir Everard Home has published a contrary ob- 
servation, that around a shell which he examined, there 
was a glairy and oviferous band, which he supposes to come 
from the body of the animal. His opinion too, founded 
on this observation, is that the animal never touches the 
ground, and that nature has thus given it the faculty of 
rolling its eggs around the shell. 
According to M. Bosc, who has had occasion to observe 
many of these animals, the janthine are eminently phosphoric. 
They serve as food to fish and birds. The violet liquid which 
they produce might be employed with equal success as that 
of the purpura, with which doubtless it has much analogy. 
Ina supplement necessarily confined to such limits as ours, 
