174 AFFINITIES AND GEOGRAPHICAL 



in that secondary formation, where all the other reptilian 

 forms so greatly abounded. Such harmonies may always be 

 expected where the true track of natural investigation has 

 been arrived at. 



A naked moist skin, sometimes smooth, sometimes covered 

 with papillae or tubercles, is the only universal character of 

 the third division of the Reptiles the BATRACHIA, so called 

 from the Greek word for a frog, as that animal is the most 

 conspicuous example of the order. The animals of this order 

 are also remarkable for coming into active existence in a fish 

 form (the tadpole), and passing in the course of active life 

 through one of those metamorphoses which in other animals 

 are undergone before birth. They realize, as has been said, 

 before our eyes, one of the grade transitions presumed by the 

 development theory. In some species, however, certain por- 

 tions of the organization are arrested at the fish stage, and so 

 continue through life. 



The frogs and toads (Eanidce) are the batrachians most 

 universally diffused over the earth and most familiarly known. 

 They are harmless creatures, generally of small size, living upon 

 slugs and insects, which they catch by darting out their long 

 soft tongue, the end of which is, for this purpose, covered 

 with a viscid fluid. They hibernate in mud or water, thus 

 living a long time, not only without food, but without aerial 

 respiration, a proof of the low organic character of these ani- 

 mals. The frogs spend much of their time in water ; some 

 assume a partially arboreal life, and have certain peculiarities 

 in the feet which assist them in climbing. The toads are 

 more terrestrial in their habits ; but all alike have to propa- 

 gate in the water, where their shell-less eggs are deposited in 

 long strings, a single mother producing upwards of a thousand 

 young. Some foreign species of the ranidse greatly exceed 

 ours in size ; but, in comparison with the two other reptilian 

 orders, the batrachian may be said to consist of little animals. 

 Teeth are wanting in most of the toads, and they are developed 

 on a humble scale in the frogs. The whole of the ranidae 

 are destitute of tail ; neither have their toes any armature, ex- 



