258 ZOOLOGY. 
simplest and most efficacious way is to tie three large hooks back to back, 
and affix a piece of red flannel, at which, especially in bright, sunshiny 
weather, the frog will often spring with great avidity, and thus hook itself. 
Of the 16 genera into which this family is divided, but three are natives of 
North America, one of them being peculiar to it. The first genus, Rana, 
or true frog, has the large fleshy tongue divided more or less posteriorly 
into two cornua or branches, capable of considerable motion, and used in 
capturing the food of the animal, by which character it is distinguished 
from all the other genera’ Species of this genus are quite numerous in 
North America, one of them, Rana pipiens, known as the bull-frog, 
attaining to an enormous size, and celebrated for the loud bellowing audible 
at a great distance. Individuals have been seen that measured 22 inches 
between the ends of the extended extremities, and even this size has been 
exceeded. The next largest species is the A. fontinalis, distinguished 
from the first by the presence of a fold of skin running along the side of 
the animal. The other species are not very conspicuous excepting the 
Rana sylvatica, or wood frog, an animal often found in damp woods 
among the leaves, and exciting attention by its yellowish color, and black 
stripe on the sides of the head passing through the eyes, as also by the 
extreme agility of its movements. The A. temporaria of Europe (pl. 81, 
jig. 34) 1s exceedingly like it, the principal difference lying in a smaller 
tympanum. Another European species, R. esculenta, is shown in pl. 90, 
fig. 5. This, like all the true frogs, or Rane, has a membrane between 
“the hind toes to assist in aquatic propulsion. The number of eggs laid by 
the frogs is very considerable, in some cases amounting to several thou- 
sands. They are generally deposited around some aquatic plant enveloped 
in a gelatinous mass. When the ova are ready for exclusion, the male 
mounts upon the back of the female, and as the eggs are discharged ejects 
a small quantity of seminal fluid into the water where the operation takes 
place—this sometimes occupying days and even weeks, during the whole 
of which time the pair thus remain attached. The egg after passing 
through the embryonic changes appears as a larva, all head and tail, with 
simple entire gills which soon disappear, to be followed by others of more 
- complicated structure, situated within the cavity of the body as in fishes. 
After a certain length of time the hind legs begin to appear, and still later 
the forelegs are found to exist, fully formed beneath the skin, ultimately to 
burst forth. The tail then disappears by absorption, this taking place very 
rapidly. A remarkable interna] transformation takes place during these 
external changes, from the herbivorous tadpole to the carnivorous frog. 
The reproductive history of nearly all the Batrachia anoura is very similar 
to that just described, with special modifications, to be referred to under 
the proper head. ) 
The genus Scaphiopus, with much of the appearance of a toad, is yet 
distinguished by the teeth in the upper jaw. There is a cartilaginous pro- 
cess on the hind foot, serving the purpose of a shovel in excavating the 
holes in which the animal dwells. The toes are palmated, and the tongue 
nearly entire. Cystignathus is well distinguished by the entire absence of 
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