284 Dr. H. Lacaze-Duthiers on the Float of the Yanthine. 
from its float, I remarked that when the first movements pre- 
ceding its being placed in this position ceased, and the animal 
believed itself out of danger, it issued by degrees from its shell, 
extended its foot, and commenced the manceuvres described 
above. I had the satisfaction of seemg the opinion that I had 
formed confirmed in every point, by observing the animals in 
these normal conditions; for I was able to be present, with the 
help of patience, at the origin and formation of a float. I saw 
that, in proportion as one bubble was added to another, the ani- 
mal became specifically lighter, and was less immersed in the 
water. And I ascertained that, under these circumstances, the 
Tanthine which could not reach the surface made vain efforts 
and movements to form bubblés; and when, under these cir- 
cumstances, I very gently raised the shell by means of a small 
hook, as soon as the foot issued from the water, air was impri- 
soned, a bubble added to the float, and the animal began to re- 
ascend. Now, nothing of this could have taken place without 
the assistance which I gave it. 
I have had many individuals of which the floats, being par- 
tially destroyed by storms, were insufficient to bring the body of 
the Janthina near enough to the surface, and allowed the ani- 
mals to perish floating at mid water, exactly like those which 
fell to the bottom of the vessels when completely deprived of 
aériferous vesicles. 
Dr. Coates, cited by Forbes and Hanley, and already men- 
tioned, supposes that the young Jantline, on issuing from the 
capsules suspended beneath the float, in which they passed their 
first embryonic period, get upon the back of the float, and then 
attempt the formation of the apparatus which subsequently en- 
ables them to do without their mother. This supposition, from 
what we have just seen, appears to be perfectly legitimate as a 
supposition. Nevertheless, as this matter is not proved by 
direct observation, we must not forget that the Gasteropods in 
an embryonic state have locomotive organs, which enable them 
to move about, and to come even to the surface of the water ; 
for they are very active. It may be, therefore, that at the mo- 
ment when the organs of locomotion bring the young lanthine 
to the surface of the water, they begin to form with their foot a 
few bubbles containing air which serve as their first floats. 
As all authors have stated, the floats of the Janthine are deli- 
cate; they must be affected by the attacks of the numerous and 
voracious inhabitants of the sea, and consequently they must 
also be constantly repaired. It is plain, indeed, that constant 
secretion would either be too late for the necessities of the 
economy of the animal, or in advance of it, producing a too 
great and inconvenient flotation. Hence the restoration of 
