S^ Observations on the Natural History 



four on each side, and their margins are furnished with small 

 points, — in the proteus, there are but three on each side, and 

 these are smooth. The arches of the proteus have an osseous 

 structure, — those of the siren and larvae are cartilaginous. 

 This difference did not escape M. Cuvier, who, speaking of the 

 proteus, says, " Tapparell osseux qui porte les branchies, est 

 beaucoup plus dur que ne Tavons trouve dans la slrene, et dans 

 Vaxolotl-''' and in his anatomical description of the latter ani- 

 mal, he farther says, " Vappareil qui supporte les branchies a 

 de grands ra-pports avec celui de la sirene, et je crois que, lors 

 de la metamorphose, il en reste une partie pour former Tos 

 hyoide de la salamandre *." Now, if the branchial arches of 

 the siren be, as M. Cuvier asserts, entirely cartilaginous, al- 

 though the cranium, the lower jaw, and the vertebrae be per- 

 fectly ossified ; and if these arches, both in form and number, 

 be similar to those of the aavlotl, which M. Cuvier himself 

 regards as a larva, — may it not be presumed that the former 

 animal is a larva also ? If, farther, the branchial arches of the 

 proteus, which is a perfect animal, be osseous, and entirely dif- 

 ferent from those of the siren and all the larvae hitherto known, 

 have we not in these facts the strongest reasons for regarding 

 the siren as an imperfect animal, and, therefore, essentially dif- 

 ferent from the proteus ? 



With regard, next, to the organs of circulation, there are, in 

 the larvae of the frog and salamander, as many arteries given 



* The authors here observe, that they have not themselves had an opportu- 

 nity of anatomising the sirena lacertina ; and, therefore, with regard to its inter- 

 nal structure, they trust entirely to the descriptions of M. Cuvier, who has writ- 

 ten largely upon it. 



It may not be out of place to add, that, in the new arrangement of M. Cu- 

 vier, the Proteus anguinus stands in the class Reptiles, — order Batraciens, — 

 genus (containing as yet only one species,) Proteus. Besides internal lungs, it 

 bears externally, like the larva of the salamander, three gills on each side of the 

 neck, which it appears to retain through life. 



The Sirena lacertina occupies the same class and order, and is another genus 

 consisting only of one species. It is said, like the proteus, to retain through its 

 whole life, three gills on each side the neck, and to possess, at the same time, 

 lungs internally. 



In the same class and. order is placed the Axolotl of the Mexicans, or Sirena 

 pisciformis of Shaw. It belongs to the genus Salamandra, of which it is a spe- 

 cies. Some allege that it also always retains its gUls. — Vide Le Regne Animal^ 

 tom. ii. p. 101,-102. — Transl. 



