The Bull-Frog (Rana pipilus), of North America, is from six to eight inches long and from three to four inches broad. When his limbs are fully extended he measures about eighteen inches in length. Its back is of a sombre green colour, varied with black; the under-parts being of a whitish hue, tinged with green, and thickly spotted. The fore-feet have only four toes, and are unwebbed; the hind-feet are large, long, and widely webbed. Its voice may be compared to the distant lowing of a bull, and a chorus of them at night is sufficient to arouse the soundest sleeper. They prey upon ducklings, goslings, and small birds, drowning before devouring them. Spite of its size and ungainliness, it is very nimble, and can accomplish a leap of upwards of six feet in height.
Incomplete as is this rapid survey of the Fauna of the New World Deserts, I cannot terminate it without referring to the strange and formidable fish which haunt the pools, lakes, and marshes of South America—those Gymnoti, or Electrical Eels, sometimes five, six, and even eight feet long, which emit electrical discharges of sufficient violence to strike down a man, a horse, or an ox. It is by this singular property the gymnotus supports its existence; its shocks stupify the smaller fishes and other animals that come within its range, so that they fall an easy prey to its voracity. The electrical organs consist of four bundles of parallel membranaceous laminæ arranged along the inner side of the tail, and constituting a remarkably powerful battery.
In hunting the gymnoti the Indians adopt a cruel expedient. They drive a herd of horses and mules into the ponds which these eels inhabit, and harpoon them when they have spent their electrical force on the unhappy quadrupeds. The fish swim on the surface of the water like serpents, and skilfully glide beneath the animal’s body, discharging the whole length of their electrical battery, and attacking simultaneously the digestive viscera, and, above all, the gastric plexus of nerves. Fain would the horses escape their enemies’ attacks, but the Indians drive them back into the water with stout canes of bamboo and long whips. After awhile the eels grow exhausted; the animals show less alarm; and the Indians begin to ply their harpoons with equal agility and success. There are several species of this remarkable fish, and most, if not all, are valued as wholesome food. The Gymnotus Electricus, however, is the only one which possesses any electrical powers.
CHAPTER XII.
ANIMAL LIFE IN THE AUSTRALIAN PRAIRIES.
THE first naturalists who explored the littoral of the Australian continent and its adjacent islands were struck with astonishment at the sight of the strange and almost monstrous animals they discovered there. Far more certainly than Columbus had they fallen in with a New World; a new world of zoology and botany; a world apart, peopled by beings wholly different from those they had elsewhere studied, and some of which exhibited a complexity and originality of organization and structure wholly antagonistic to the received theories of fundamental characteristics belonging to the various classes of the animal kingdom. The Australian Fauna, in this respect, can only be compared to that of Madagascar, which equally bears an impress peculiarly its own, and presents but a few features of kinship with the Indian Fauna. It is the latter also that the Australian Fauna most closely approaches, or, to speak more correctly, from which it least widely diverges.