480 CLASS REPTILIA. 



any appearance of hinder feet ; yet M. Rusconi, a learned 

 physician of Milan, has raised doubts concerning all these 

 testimonies, and thinks that the siren undergoes metamor- 

 phosis, because he was informed by a German traveller, that 

 he saw at the Museum of the College of Surgeons in this 

 metropolis, a siren with its four feet, and without any gills. 



This assertion certainly deserves the reproach of levity ; 

 this pretended adult siren was known a long time ago, and had 

 not escaped the investigating eye of Garden, and was in fact, 

 the amphiuma means, which we have already described. 



The simultaneous existence of a larynx, and trachea, 

 with a branchial apparatus not only permanent, but perfectly 

 ossified in most of its parts, is a peculiarity of high importance 

 in comparative anatomy. This is exhibited in the siren. It also 

 contributes to prove what has been advanced by M. Cuvier 

 with respect to frogs and salamanders, namely, that the 

 branchial apparatus is nothing more than a mere complicated 

 hyoid bone, and not a combination of pieces from the sternum 

 and larynx. 



Though it greatly approaches the salamanders and the 

 proteus, the siren nevertheless differs from them in a great 

 number of internal characters. Its head has neither the 

 same general conformation, nor the same proportions between 

 its parts ; the muzzle is very narrow in front, in consequence 

 of the extreme reduction of the maxillaries, which consist 

 only in a very small osseous nucleus ; behind is observable 

 an occipital crest which predominates over the petrous por- 

 tions and the parietals. 



The pieces which compose the lower jaw, are not trans- 

 verse, but are directed obliquely forwards. The inter- 

 maxillary bones have no teeth, but their trenchant edge, as 

 well as that of the lower jaw, is furnished with an almost 

 corneous sheath, which is easily detached from the gum. 



The cavity of the nasal fossa is covered underneath, with 



