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Show 76 RJ~PTILIA. There are some m• w 1n ' ell the plicre are almost eff.a ced; their bod is very long and slender, and their ~uz.zle sahent. One ~ . 1 1 bf d. the Cree. lumbnco.,dea, Daud. VIII, spec1cs 1s compete Y m ' h h' k xcii, 2; it is blackish; two feet in length, and about t e t lC • ness of a goos~-q uill. ( 1) "' ORDER IV. BArRACHIA.(2) The Batrachians have a heart composed of but one alll·i.cle and one ventricle. They all have two equal lungs, to whtch at first are added branchire, that have some affinity with .those of Fishes and which have cartilaginous arches on each side of the neck'attached to the hyoid bone. Most of them lose these branchire, and the apparatus which supports the~, when they attain a state of maturity. T&ree genera only, Siren, Proteus, and Menobranchus, retain them for life. As long as these branchire remain, the aorta is divided at its origin into as many branches on each side as ~here ~re branchire. The branchial blood is brought back by vems which unite near the back in one arterial trunk, as in Fishes. It is from this trunk, or immediately from the veins which form it, that arise most of the arteries which nourish the body, and even those which conduct the blood to be oxygenated in the lungs. In those species, however, which lose their branchire, the attendant arteries are obliterated, with the exception of two, which unite in a dorsal artery, giving, each, a small branch to the lungs. It is the circulation of a Fish metamorphosed into that of a Reptile. Batrachians have neither scales nor (1) Linna:us mentions it, Mus. Ad. Fred., V, 2, but confounds it with the ten· taculata. We have the skeleton ofu. Ca:cilia more than six feet long, and having- two hun· dred and twenty.five vertebra:, but of whose external characters we are ignorant. (2) F'rom ~rl.rr~ax_o r (Frog), animals analogous to Frogs. TIATRACIIIA. 71 she11; a naked skin invests their body,(l) and, one genus ex· cepted, they have no nails. . .• The envelope of the ova is membranous, and, in many species, they are only fecundated at the moment of their e~· pulsion. These eggs become greatly enlarged in the water. The young do not only differ from the adult in the presence of the branchire; their feet are developed by degrees, and in several species there are a beak and tail, which they subse· quently lose, and intestines of a different form. Some species are viviparous. ' '· I r. ,, RANA, Lin. Frogs have four legs in their perfect state, but no tail.. Their head is flat, muzzle rounded, and the opening of their jaws large; the tongue, in most of them, is soft, and not attached to the bottom of the gullet, but to the edges of the jaw, and folds inwards. There are but four toes to the anterior feet; the hind ones frequently exhibit the rudiment of a sixth. There are no ribs to their skeleton, and a prominent cartilaginous plate supplies the place of a tympanum, and renders the ear visible externally. The eye is furnished with two fleshy lids, and a third, which is transparent and horizontal, concealed under the lower one. Inspiration is solely effected by the muscles of the throat, which by dilating, receive air from the nostrils, and by contracting while the nostrils are closed by the tongue, compel that air to enter the lungs. Expiration, on the contrary, is produced by the muscles of the lower part of the abdomen: thus if we open the belly of one of these animals while alive, the lungs dilate without being able to contract, and if we force another to keep its mouth open, asphyxia is the consequence, as it is no longer able to renew the air in its lungs. 'fhe embraces of the male are long continued. His thumbs are furnished with a spongy enlargement which increases during the nuptial season a'nd assists in attaching him to the female. He fecun· dates the ovum at the moment of its expulsion. l'he little anLmal that is produced from it, called a Tadpole, is at first furnished with a long fleshy tail, and a small horny beak, having no other apparent limbs than little fringes on the sides of the neck. In a few days these disappear, and Swammerdam assures us that this is owing ( 1) M. Schneider has proved that the Scaly Frog of W albaum only appeared so from accident, a few scales from some Lizards that were kept in the same j:u· having adhered to its back. Schn. Hist., Amphib. Fasc. J, p. 168. \ |