178 FOURTH REPORT — 1834, 



purely anatomical, it would be out of place to dwell on them in 

 this Repoi't. Yet we may allude to one as of more impoilance 

 to zoology than some others. I refer to Dr. Davy's discovery 

 of a second auricle in the heart of these animals, which will lead 

 us to correct what was always considered as one of their distin- 

 fifuishing characters, viz., their having a single heart like Fishes *. 

 The Perennihranchiate Amjihihia received some time back much 

 illustration from Cuvier, whose researches on this subject will 

 be found in the first volume of Humboldt's Comparative Anato- 

 myt He was led to regard the Siren and Proteus as adult 

 animals, bat suspected the Axolotl to be a larva. In 1819, 

 MM. Configliachi and Rusconi published a valuable monograph % 

 on the Proteus anguinus, containing a full account of the struc- 

 tvire and natural history of this singular animal. Dr. Rusconi is 

 the author of another work, published in 1821 §, in which he has 

 treated of the tiquatic Salamanders, detailing some interesting 

 observations respecting the mode of development of these Rep- 

 tiles. This subject had not been previously followed up with 

 so much closeness of research. It may be stated that in this last 

 work Dr. Rusconi has doubted the accuracy of Cuvier's views 

 respecting the Siren being an adult animal. Cuvier has recon- 

 sidered the subject in his Ossemeus FossiIes\\ ; but still adheres 

 to his former opinion on this point. From examining the os- 

 teology of this reptile, he feels satisfied that it never acquires 

 hind feet, as Rusconi supposes, and deems it very improbable 

 that it ever changes its form or loses its branchiae. That the 

 Siren is not the larva state of the Amphiuma of Garden, as 

 some imagine, Cuvier has endeavoured to prove in a memoir 

 upon this last genus published in the Mem. du Mus.% for 1827- 



* Edlnh. New Phil. Journ. 1828, p. 160. Dr. Davy's researches went no 

 further than to show the existence of a second auricle in several species of the 

 genus Rana; but reasoning from analogy, he thought it probable that the same 

 would be the case in all the other genera of this group. These suspicions have 

 been since partly confirmed by Mr. Owen, {Proceed. ofZool. Soc. 1834, p. 31,) 

 who has lately given the results of an examination of the hearts of several ge- 

 nera of the Perennibranchiate Ampbihia, in all of which he finds it consisting 

 of three distinct cavities, as in the higher Reptilia. 



f " Recherches anatomiquessurlesReptiJbs regardes encore commedouteux 

 par les Naturalistes ; faites a I'occasion de I'Axolotl, par M. Cuvier." — Humb. 

 Anat. Comp., tom. i. p. 93 — 126. 



X Del Proteo Anguino di Laurenti Monografia. Pavia, 1819. An excellent 

 analysis of this work will be found in the Edinb. Phil. Journ. for 1821, vols. iv. 

 and V. 



§ Amours des Salamandres aquatiques, et Developpement du Teiard de ce,<t 

 Salamandres, depiiix VCEvf jiisqu' a V Animal farf ait. Milan, 1821. An analysis 

 of this work also will be found in the Edinb. Phil. Journ. for 1823, vol. ix. 



II tom. V. Pt. II. p. 418, &c. 1[ tom. xiv. p. 1. 



