5$ A neiv species of Siren. 



posed to as many cartilaginous arches, the internal side ol' 

 which is rough, and furnished with cartilaginous tubercles, as 

 in fish. There is only a double branchial aperture on each 

 side, for the upper and the lower arch of the branchiae is ad- 

 nate to the skin. 



These animals, the two species of siren, the Amphiuma, 

 the Hell-Bender, the Axolotl, the Proteus, with one or two 

 others, perhaps obscurely and imperfectly described, will 

 form a family of reptiles distinct from all others, by being 

 furnished with nostrils and spiracula ; they will naturally be 

 divided into such as have a bony and solid skull, as the Am- 

 phiuma and Hell-Bender, and such as are composed of 

 many separate bones, as the Siren and Proteus, for after all it 

 is only anatomical examination that can point out the true con- 

 nexion and difference between animals. 



Observations on the teeth of the Megatherium recently disco- 

 vered in the United States. By Samuel L. Mitchill, M. D. 

 Read Nov. 17, 1823. 



Through the politeness of Mr. A. Taylor, I have received 

 some fossil teeth from Skidaway Island, (Georgia.) Many 

 bones were found with these teeth, but from the carelessness of 

 the persons who discovered them, they are dispersed or de- 

 stroyed. I can obtain no information as to their situation 

 when discovered. 



These teeth are very remarkable, and differ much from any 

 hitherto discovered in North America. In my investigations 

 I was assisted by my friend Dr. Dekay, and there can be no 

 doubt that the teeth in question belong to that extinct species, 

 denominated by Cuvier the Megatherium. 



From the interesting nature of the subject, fno specimen 

 having heretofore been discovered of the Megatherium north 

 of the Equator,) it is presumed that a concise account of this 



