The amphibia grow very slowly ; the common frog, for example, in general, cannot procreate until it has attained its fourth year, and yet it probably does not live beyond 12 or 16 years. The tortoise lives, even in a state of captivity, above an hundred years; and we may infer from analogy, that large serpents and crocodiles may reach a still greater age.
Some of the animals of this class are eminently useful to the inhabitants of certain countries: the eggs and flesh of the turtle afford a very delicious and nourishing food; and certain species of frogs and lizards are con sidered as delicacies, and in some countries are con sumed in very considerable quantities. 'Flie shell ()I the tortoise is employed for a variety of purposes.
Many of the amphibia, as the crocodile, are danger ous on account of their vast size and great strength; others, particularly among the serpent tribe, are dan gerous on account of their poison; but the number of poisonous serpents is not so great as was formerly ima gined; perhaps, as Dr Shaw remarks, not more than it sixth of the whole number of known species being of that character.
The jaws of serpents are extremely dilatable, and the (esophagus so lax, that they can swallow, without mas tication, all animal twice or thrice as large as the neck.
In the Linirxan arrangement, the amphibia are divi ded into four orders, viz. 1. Mntiles pedati. 2. Serpen ces apodes. 3. Meanies. 4. AiinIes. The reptiles pe dati have four feet, and they walk as if creeping; the serpents have no feet, and they crawl upon their belly ; the names have fins, and swim; and the meantes, or gliders, according to Unmet's, have both gills and lungs, and are furnished with arms and claws. This all ange mem has been considerably improved by naturalists since Linnzeus's time. The amphibia ?zanies have been placed amongst the true fishes, because they have a similar internal structure and external aspect. They form a particular division under the title cartilaginous fishes, which is subdivided into two orders, the chon dropterygii, and branchiostegi; the order chondroptc rygii contains the following genera, petromyzon, gastro branchus, raja, squalus, lophius, batistes, and chimxra; the order branchiostegi, the genera accipcnser, ost•a cion, tet•odon, diodon, cyclopterus, centriscus, syngna thus, and pegasus. The order meanies is abolished, and the animal on whose account it was established, the siren, is placed near the salamander, and other species of reptiles pcdati. The whole class is now divided into two orders, viz. reptiks and serpcnIes. The order of reptiles is subdivided into four genera, viz. testudo, (Ivaco, lacerta, and rani; and that of serpentes into nine genera, viz. crotalus, boa, colubcr, anguis, amphisbcena, caecilia, acrochordus, hydrus, and langaya. This im proved arrangement, first proposed by Blumenbach, has since been followed by Gmelin, Shaw, and other zoolo gists, and is the best hitherto proposed.
The naturalists of the French school have proposed arrangements different from that of Blumenbach: to give an account of all these would exceed our limits, and merely to enumerate them would be useless; we shall therefore confine ourselves to a very short account of the latest arrangement, viz. that of Dumeril, the pu
pil of the illustrious envier, as stated in his 7, ,;logic .1nalytigue. According to this arrangement, the amphi bia are divided into four orders, named cheloniens, sau ophidiens, and batricicns.
The order cheloniens (from ;fit? 'a, tortoise) is thus characterised; body short, oval, arched, covered with a shell, having four feet, and without teeth. It contains the following genera, chelonia, chelus, cmys, and tes tudo; the genus chelonia, includes all the species of sea turtle, and also those that inhabit salt lakes; the genus chelus contains but a single species, the testudo fimbri ata of Schceff ; the genus cmys, those species that inha bit rivers, rivulets, and fresh-water lakes ; and the genus tc,Nr tido, those species that live upon the land, and even in the sea or rivers.
The second order sauriens, (from 7.',(40;61, lizard,) is thus characterised; body without a shelly covering, four feet provided with crooked nails, jaws armed with teeth. It is subdivided into two families, 1 iz. planicaudes and terctecaudes; which distinctions are founded on the shape of the tail, it being flattened horizontally or per pendicularly in the planicaudes, which generally live in the water, and conical or cylindrical in the teretceaud, s, that live on the land. The planicaudes contains six genera, viz. crocodilus, dracx.na, tupinambis, uroplatus, lophyrus, and basiliscus; the terctccaudes contains ten genera, viz. iguana, draco, agama, stellio, anolis, lacerta, scincus, chalcides, gecko, and eturixlio.
The third order, ophidiens, (serpentes,) is thus cha racterised ; body elongated, narrow, without feet or fins, jaws provided with teeth. It is subdivided into two fa milies, viz. homodermes and heterodermes; the hoino dermes is either destitute of scales, or the scales over the whole body arc alike ; the mouth is small, the jaws not dilatable, and it is destitute of venomous fangs or tusks; the heterodermes family has the skin covered with small scales above, with scuta beneath, with dilata ble jaw s. The homodermes contains six genera, viz. cxcih a, amphisbcena, achrocordus, ophisaurus, anguis, and hydrophis; the heterodermes contains eight genera, viz. erix, erepton, boa, coluber, vipera, scytales, crota Ins, and platurus.
The fourth order, batriciens, (from Barmo5,ftog,) is thus characterised ; body naked, without scales or shell}' covering, feet without claws. It is subdivided into two families, viz. anoures (ecaudati), and urodeles (caudati); in the first family the body is large, without a tail, and the fore feet are much shorter than the hinder feet ; in the second family the body is elongated, provided with a tail, the fore feet of equal length, and the tongue ad hering. The family of anoures contains four genera, viz. pipa, bufo, rani, and hyla; the family of urodeles also contains four genera, viz. triton, salamandra, pro txus, and siren. It is evident, that in this arrangement, not only the genera, but also the orders and families are unnecessarily multiplied, and therefore, that the more simple, and equally accurate system of Blumen bach is to be preferred. (r)