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m the larva, are very long. Before the forelegs become completely 

 formed, those behind sprout out in a similar manner, with first three, then 

 four, and finally five toes. During this time the gills have increased in the 

 number of branches, and finally exhibit a beautiful arborescent appearance, 

 in which the circulation of the blood can be distinctly seen by means of a 

 simple lens. At the time, then, that the individual has attained its perfect 

 larval state, it has four legs, with four fingers on the anterior, and five on 

 the posterior ; the jaws are wide, the mouth well provided with teeth ; the 

 superior maxillary bones, however, not developed, and the pterygoid bone 

 with card teeth, as in Proteus, Menohranckus, and Siren. The animal 

 presents a perfect fac-simile of the Mexican axolotl, which, although by 

 many naturalists considered to be a permanent form, is, in all probability, 

 only a larval state of some very large species of salamander. Our animal 

 is now exceedingly voracious, devouring tadpoles, and weaker larvae of its 

 own species, with great avidity. Its entire food, in fact, has consisted 

 throughout of animal matter in some form or other. This state of things, 

 in all probability, continues from one spring to the next, or for nearly a 

 year : at the expiration of which time the gills will be seen to wither 

 gradually away, the lateral holes in the neck to grow together, and all 

 these traces of larval life finally to disappear. The superior maxillary 

 becomes developed and ossified, the temporary teeth in the roof of the 

 mouth vanish, the lungs acquire a great development, yellow spots break 

 out of the dark ground of the body, and finally the animal leaves the water, 

 never to return to it again except for a short period in the spring oi the 

 year, when it is engaged in the function of reproduction. Such is a brief 

 outline of these changes, which vary in different genera and species. 



Proceeding now to the more particular consideration of the Batrachia 

 urodela, we commence, first, with the sub-order Trematodera. Here we 

 find that the apertures in the side of the neck remain open throughout life, 

 and in several genera even the gills are persistent. The first genus that 

 would come properly here is that of Siredon, or the Axolotl, whose distin- 

 guishing characteristic is to be found in the opercular flap being detached 

 from the subjacent integuments, and continuous across the throat. The 

 gills and gill-openings are very highly developed, the tail strongly com- 

 pressed, and provided with a well developed fin. Toes, four in front, five 

 behind, all much elongated. Two species have been described, the one S. 

 mexicanus, from the lakes in the vicinity of the city of Mexico, the other 

 S. maculatus, from the New Mexican Rio Grande. For reasons above 

 mentioned, we prefer to consider them as larvae, and proceed to the 

 consideration of the genus Proteus. The single species of this genus, 

 P. anguinus, has long been an object of great interest to naturalists, on 

 account of its individual features, as well as the circumstances under 

 which it is found. It is an inhabitant of the subterranean waters of 

 Sittich in Lower Carniola, and of the great cave of Adelsburg on the main 

 road from Trieste to Vienna. Occasionally it has been caught in the 

 external outlets of these waters, but, like the blind fish of the Mammoth 

 Cave of Kentucky, its usual residence is at a distance of some miles from 



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