The generio characters of the genus Cuvier (A xolotes, Owen, Gyrinus, Hernandez), in addition to those above mentioned, consist in having the gills formed of three long ramified or branchlike pro cesses on each side of the neck, four toes on the anterior extremities and five on the posterior, and teeth in the vomer as well as in both jaws. The tail is coudproxsep on the sides like that of the common Water Newt (Salarnandra palmate), and surrounded both on the upper and under surfaces by a thin erect membriumus fin, which is prolonged upon the back, but becomes gradually narrower as it approaches the shoulders, between which it finally ceases. The head is broad and flat ; the nose blunt ; the eyes situated near the muzzle ; the tail nearly as long as the body ; and the toes unconnected by intermediate membranes. The singular form of the gills will be boat understood from the accompanying figure, which represents the under jaw and 'throat of the animal as seen from beneath.
The Aro/ot/ of the Mexicans (Gyrinus (dulls, Hernandez), when full grown, measures about 8 or 9 inches in length ; its ground colour is a uniform deep brown, thickly mottled both on the upper and under surfaces of the head and body as well as on the limbs, tail, and dorsal and caudal fins, with numerous small round' black spots. The head
and body are larger and broader than in the generality of reptiles, and but for the long tail which terminates the latter the whole animal might be not inaptly compared in form to a large frog; the gills are prolonged into three principal processes, with numerous smaller ramifications from the sides of each, the whole being as long as the fore legs, and resembling three small branches ; the logs are short, though fully developed ; and the toes are long, slender, separate, and without claws. The communications which open from the gills into the mouth are four in number, and of a size considerably larger than those of the kindred genera ; they are covered externally by a species of operculum formed by a fold in the skin of tho head.
The Axolotl is very common in the lake of Mexico, and, according to Baron Humboldt, likewise inhabits the cold waters of mountain lakes at much greater elevation above the level of the sea than the plains surrounding that city. It is commonly sold in the markets of Mexico, and esteemed a luxury by the inhabitants. It is dressed after the manlier of stewed cols, and served up with a rich and stimulating sauce.
Professor Owen has described a second species under the name of Axolotes maculate, which also is an, inhabitant of Mexico.