180 
ANIMAL CURIOSITIES 
bottle-shells (Ampullaria) that are found in 
the marsh districts of tropical countries, for 
not only can they exist equally as well in 
water as on dry land, but they are also provided 
with both lungs and gills which enable the 
creatures to indulge in a double means of 
respiration, namely, by extracting the oxygen 
held in the water, and by taking a supply direct 
from the atmosphere. Professor Semper states 
that they make use of their gills and lungs in 
regular alternation, “ for a certain time they 
inhale air at the surface of the water, forming 
a hollow, elongated tube by incurving the 
margin of the mantle, so that the hollow surface 
is closed against the water and open only at 
the top. When they have sucked in a sufficient 
quantity of air, they reverse the margin of the 
mantle, opening the tube, into which the water 
streams.” When living entirely out of water 
the creatures, of course, only make use of their 
lungs for breathing purposes. Like the edible 
snail, ampullaria is sometimes called the apple 
snail because of the globular nature of its 
shell. It can live for a long time out of water, 
some having been kept for several years out of 
that element. 
Inhabiting Africa, Madagascar, New Caledonia 
and other adjacent islands are some enormous 
land snails that sometimes attain to a length 
