62 



the poison occupies this cavity ; and the similarity of the form and 

 structure leads to the idea that it may be used for the same purpose 

 in the Proteus of the Lakes. 



The chief difference between the teeth of the Proteus of the Lakes 

 and the fangs of Serpents, is, that in the former the upper aperture 

 of the cavity is nearer to the centre of the tooth, some distance 

 from the apex, while in the fang of the Serpent it is generally near 

 to the tip. J 



I know of no other instance of a Batrachian having this structure 

 of its teeth, nor do I know any instance, except in the Mexican 

 Lizard, called Heloderma horrida, in which all the teeth are uni- 

 formly furnished with a basal cavity and foramen ; and this Lizard 

 is said to be noxious, but the fact has not been distinctly proved. 



2. When Dr. Barton, in his paper on the Siren, first described 

 the Hell-bender (Protonopsis horrida), he considered the Proteus of 

 the Lakes as the young state of the latter species. 



The skull bears more affinity to the skull of that animal than to 

 any other Batrachian, and the difference between them is just such 

 as one might expect between the larva and adult of other similar ani- 

 mals ; and it will be observed that the Proteus of the Lakes is only 

 known in its larva-like state, and Protonopsis, as far as I know, only 

 in its *adult form. / 



The first great, and indeed almost insurmountable, argument 

 against regarding the Proteus of the Lakes and the Hell-bender as 

 two states of the same species, is the geographical distribution of the 

 animals as given by the American herpetologist. 



Thus Holbrook, for example, states, " The Menopoma Alleghanien- 

 sis (Hell-bender) is found in the Alleghany river and its tributaries, 

 and doubtless inhabits many of the branches of the Ohio and Missis- 

 sippi rivers ; " and M.fusca, " the waters of the mountainous regions 

 of North Carolina and Georgia ; " while the Proteus of the Lakes 

 (Menobranchus maculatus) has as yet been found only in Lake 

 Charnplain and Lake Erie and their tributary streams. 



It is true that a second species of the genus, Menopoma lateralis, 

 according to Dr. Holbrook, " has a wide range, it being found in many 

 of the rivers and streams that open into the Mississippi on its eastern 



