112 RANADA. 
of a different kind. It is somewhat remarkable that my 
father, who was no systematic naturalist, but a very ac- 
curate observer, should have detected, when a boy, now 
more than eighty years since, the distinction of the har- 
vest mouse and of this species of Frog. The peculiarity 
in the croak of the male is accounted for by the existence 
of the large vocal sacs, to which farther allusion will be 
made. 
The Rana esculenta may be at once distinguished from 
R. temporaria by the absence of the large distinct black 
mark, which in the latter species occupies the space ex- 
tending from the eye to the shoulder, and by the existence, 
in the present species, of a light line running the whole 
length of the middle of the back; the marbling also in 
R. esculenta is much more distinct, varied, and beautiful, 
and consists partly of circumscribed round spots. The 
vocal sacs, which are peculiar to the males, become, when 
filled with air in the act of croaking, large globular, blad- 
der-like sacs, standing out one on each side of the head, 
which do not exist at all in &. temporaria: the vomerine 
teeth are placed rather farther back in the common species. 
I have observed in #. esculenta a pair of lumbar glands, 
which, although less conspicuous, occupy the same position 
as in the genus Pleurodema of Tchudi. 
