Rana and Bufo. 175 
Four fingers or toes are found upon the anterior extremi- 
ties, while those of the posterior are five in number and 
webbed. The front legs are much shorter, smaller and 
weaker than the hind ones, which are largely developed, 
and thus serviceable in swimming and leaping. 
Though the frog is possessed of a back-bone, yet he has 
no ribs. Being ribless, he cannot expand and contract his 
chest in breathing, but must swallow what air he requires. 
In swallowing the air he must close the mouth and take the 
air in only by the nostrils; therefore, oddly enough, if his 
mouth is forcibly kept open, he will smother. The frog’s 
breathing, a fact not generally known, is partly through his 
skin, which gives off carbonic acid gas; and moisture, there- 
fore, is just as essential to his skin as it is to the gills ofa 
fish. Damp, rainy weather is his extreme delight. When 
the rain falls, out come the frogs. Their skin absorbs moist- 
ure, which is stored up in internal reservoirs, and some of 
this water, when these timid creatures are alarmed by being 
suddenly seized, is ejected, but I do not think that it is 
purposely so done, as the water is not, as some people have 
fancied, of a poisonous nature. Frogs have no poison-sacs, 
and in truth no weapons of any kind. 
Open a frog’s mouth, and you will find but a few tiny 
teeth in the upper jaw and palate, which are useful for the 
partial grinding up of horny insects. His tongue you will 
discover to be a very odd affair, which is fastened at the front 
end of the mouth, the hinder part being free and hanging 
down the creature’s throat. This organ is covered with a 
glue-like secretion. When an insect is to be captured, it is 
snapped forward from the mouth, and, striking the insect, 
which it seldom fails to do, causes it to adhere as to bird- 
lime. 
A few thoughts now about the life-history of the frog. 
From egg to egg is the story. In roundish masses, upon 
sticks lying in water, or upon the leaves and stems of sub- 
merged water-plants, are the eggs deposited. The creature 
