314 THE VIVARIUM. 
imported, gradually disappear. Lord Arthur Russell suggests, 
also in Nature for 1874, a reason for this gradual disappearance ; 
for he says: ‘‘ About ten years ago I imported a basketful (of 
Edible Frogs) from the Parisian market, where they can easily 
be obtained, and turned them into a pond at Woburn Abbey, 
in Bedfordshire. They thrived and multiplied there; but our 
summers are seldom hot enough to enable the tadpole to attain 
_his full development before the cold autumnal nights set. in.” 
It is probable that the gradual decrease in the numbers of these 
Frogs is owing to their inability to withstand, as a rule, while in 
an immature condition, the severity of our winters. It may, 
however, be said by some that they do not really slowly die out, 
but being far more aquatic in their habits than are the members 
of the commoner species, they are not so readily observed. Such 
argument can only have weight with those who forget, or who 
are ignorant of, the remarkable vocal powers of the males of these 
particular Batrachians. No one, I think, could live in the neigh- 
bourhood during spring of any fairly great number of Edible 
Frogs without being aware of their presence. Their croak is so 
sonorous that they have been called, as already mentioned, 
‘*Cambridgeshire nightingales ” and the ‘‘ Whaddon Organs.” 
The male Frog, when making his peculiar cry, inflates two 
large bladder-like sacs, one on each side of its head, which then 
attain a size much larger than that of an ordinary pea. These 
vocal sacs are not possessed by the common Frog. The Edible 
Frog uses its voice by both day and night. 
R. esculenta is a very handsome animal, and an interesting 
inmate of a Vivarium where, with care and proper treatment, it 
will live for many years. Owing to its great fondness for water, 
it must be provided with a fairly large tank, where, however, it 
will not by any means spend all its time. 
It is an animal with a large appetite, and sometimes, indeed, it 
brings shame upon its species by stooping to the low habits of a 
cannibal, and devouring a small brother Batrachian in the shape 
of a half-grown Frog or an immature Newt. Nevertheless, I think 
if it be given the choice, it will invariably prefer a large worm, 
instead of a tiny relative. 
The Edible Frogs in their native country inhabit rivers, lakes, 
