Naturalists have discovered and described three ani mals, uniting, as is the case with the tadpole, the two kinds of respiratory organs, and not appearing to lose them at any period of their life, and of such a size that they cannot be considered as the larva of any animal in the country where they are found. These aainsals arc the siren lacertina, Lin. the axolotl, or siren piscitOrmis of Shaw, and the proteus. Are these three genera then, as asserted by naturalists, perfect animals, true. perma nent amphibia ? Ought they to be considered as forming a class intermediate between the amphibia and pisces ? The detail of the answers to these questions will be found under the proper articles ; we shall here only state the general result obtained by Coyle'', in his ex aminations of the external aspect and internal structure of those interesting animals. He found, after a careful examination of the external aspect, osteology, and or gans of circulation, respiration, digestion, generation, and sensation of the siren lacertina, Lin. 1. That this animal, whatever state it may afterwards attain, is dif ferent from the salamander either in its perfect or larva state. 2. That it does not appear to acquire hinder feet, but remains a biped reptile. 3. That it dues not appear to lose its branchix ; and that no one, even in the coun try where it lives and abounds, has hitherto found a specimen without branchix. 4. That it is essentially different from fishes in its osteological structure, and the organization of its 5. That it appears to form a particular genus in the order of reptiles, in which both branchix and lungs arc permanent ; and that we may consider it as a permanent larva of that order.
In regard to the axolotl, or siren pisciformis of Shaw, he concludes, that it is probably the larva of some large species of salamander. In regard to the proteus, he remarks, that every observation proves it to be a parti cular species, different from all hitherto known, and that very probably it is an adult animal, which does not change its state. It therefore follows, that the axolotl
ought to be erased from the list of perfect animals, and be considered as a larva, and that the two others, viz. the siren lacertina and proteus, are to be considered distinct animals, which, to all appearance, do not change their state, and consequently form genera, which are in some respects intermediate between the order reptiles, of the class amphibia, and the order chondroptcrygii, of the class pisces : so that we have thus two genera of perfect animals, which appear, in the strictest sense of the word, to be amphibious. The protcus and siren are, by Dumeril, placed in the family urodeles (caudati), of his order Batraciens, along with the salamander and tri ton.—See Observations on the class of Animals called by 1,17711X118 amphibia ; particularly 071 the means of distin guishing those Serpents which are venomous from those which arc not so, by G. W. Gray, M. D. Phil. Trans.
vol. 79, p. 21-36.
Peter Boddart's Abhandlungen von amphibien. Schr. der. Berlin. Ges. Fr. 2 Band. p. 369-387. Bla sius Meerem's Bcitriige zur geschichte der .dm/zhibien. Leipzig, 1790. L. G. Schneider's Amphibiorum PhyAio logi.r specimen p. 82. 1790-4. *Specimen alterum, historian: et species generis, Stellionum scu Geckonum sistens, p, 54, 1792. James Parson's Observations upon Animals, commonly called Amphibious hut authors. Phil.
Tran.e. vol. 56, pp. 193,205, Geissler's Di8Autatio de 4m ;MA:8, Leipsix, 1676. R. Tounson's Phy siologicer dr .dmphibas,Goettingx, 1794, 1793. /?echerche...
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