ORDER IV. BATRACHIA.—FROGS AND TOADS. 157 
where to be found among existing species, and, consequently, we may con- 
clude never had a being except in fable. And yet this most stupid and dis- 
gusting of all creatures was, in many ancient systems, as the Eeyptian and 
Scandinavian, an emblem of the conservative power of Nature. A Chris- 
tian sect was called by its name (the Ophidians), and employed serpents in 
their religious ceremonies as a type of the Infinite Wisdom. Traces of 
snake worship may also be found in the Old Testament. With our instine- 
tive antipathy to the serpent, and the experience of that crawling horror 
which its presence, and even the thought of it, inspires, we cannot conceive 
how any human beings could ever have regarded it with other feelings, and 
much less how they ever could have received it as a symbol of wisdom and 
goodness. On the contrary, we feel that the terrible hideousness of the forms 
of all, and the poisonous character of some, might well represent the Evil 
Principle of the universe. 
ORDER IV. BATRACHIA (Frogs and Toads). 
The Batrachians, according to Cuvier, have but one auricle and one ven- 
tricle to the heart, which, however, is disputed by Professor Owen. Their 
two lungs are always equal (we here follow Baron Cuvier), and when young, 
they conjoin to their gills, which give them a relationship with the class of 
fishes. The creater number lose these gills upon attaining the perfect state, 
the only exception being the Syrens, the Protei, and the Menobranchi, 
which retain them at all ages. During the period of the retention of the 
gills, the aorta, on proceeding from the heart, divides into a number of 
branches upon each side, corresponding to that of the gills, the blood from 
the gills returning through veins, which unite together towards the back into 
a single arterial trunk, as in fishes. This trunk supplies the greater number 
of the arteries which nourish the body, and even the vessels which conduct 
the blood for respiration into the lungs. But in the species which shed their 
gills, the vascular ramifications that communicate with them become obliter- 
ated, excepting two, which unite together to form a dorsal artery, each 
giving off a small branch to the lung of its particular side, so that the cir- 
culation of a fish becomes thus converted into that of a reptile. 
The Batrachians have no scales, but are clothed with a naked, smooth, 
and moist skin, and, excepting one genus, have no nails to their toes. The 
eggs are laid in the water, and the young bear little or no resemblance to 
the form which they assume at maturity. Some of the species are vivip- 
arous. 
Genus Rana. —The Frogs. The Frogs are the most numerous, and 
