FROGS. 17 
Serpents are eaten. But viper-broth, which was known to Hippo- 
crates, we believe, is not to be found now as an article of food. 
As we have already remarked, the peculiar nature of their 
organisation leads Reptiles and Batrachians to seek the warmer 
regions of the earth. It is in those regions that they attain the 
enormous dimensions which distinguish certain Serpents ; there, too, 
they secrete their most subtle poisons and display the most lively 
colours, which, if less rich than those of Birds and Fishes, are not’ 
less startling in effect. Many Serpents and Lizards glitter with 
radiant metallic reflections; and some of them present extremely 
varied combinations of colour. Chameleons are found in the same 
localities, but in the Old World only; these and some other Lizards 
are remarkable for changing their colour, a phenomenon which is 
also seen among the Frogs, but ina smaller degree. 
Reptiles and Batrachians were numerous in the early ages of our 
globe. It was then that those monstrous Saurians lived, whose 
dimensions even are startling to our imagination. The forms of the 
Reptiles and Batrachians of the early ages of the earth were much 
more numerous, their dimensions much greater, and their means of 
existence more varied than those of the present time. Our existent 
Reptiles are very degenerate descendants of those of the great 
geological periods, unless we except the Crocodiles and the gigantic 
Boas and Pythons. Whilst the Reptiles of former ages disported 
their gigantic masses, and spread terror amongst other living 
creatures, alike by their formidable armature and their prodigious 
numbers, we are happy to say that now they are reduced to fewer 
varieties. There are now but little more than 1,500 species of 
Reptiles and Batrachians described, and only 1oo of these belong to 
Europe.* 
BATRACHIA, 
Animals which compose this class have long been confounded 
with Reptiles, from which they differ in one fundamental peculiarity 
in their organisation. At their birth they respire by means of gills, 
and consequently resemble Fishes. In a physiological point of view, 
at a certain time in their lives these animals are Fishes in form, 
habits, and organisation. As they progress in age they undergo 
permanent metamorphosis—they acquire lungs, and thenceforth an 
aérial respiration. It is, then, easy to understand that these animals 
hold a doubtful rank among Reptiles, which are animals with an 
‘ 
® [ide subsequent notes on this sul ject, in p. 28, & 
