Supplement to the Zoology. 183 
We have the elaborate monography of the same animal, 
with drawings and figures of every part, by yourself,* and 
the profound inquiry into the history of the Water-Salama- 
mander and its larve by your colleague, Professor Rusconi, 
is also in our hands. 
From such a survey asI have been capable of making, I 
am inclined to consider him a Proteus; but of a species 
different from that known to European naturalists. 
The Genus, as constituted by Laurenti and Cuvier, con- 
sists of a single species, the subaqueous reptile of Carniola. 
The one I introduce to you, must be considered a second 
species of that genus, unless a further examination shall ren- 
der it necessary to constitute him a new genus. : 
You may expect to receive additional information on this 
subject, as soon as it shall bein my power+o give it. In the 
mean time I intreat you to accept favourably this humble 
contribution to the great works in which you are engaged. 
SAMUEL L. MITCHILL. 
Art. XXIV.—Detection of a mistake into which Naturalists 
have been led, in relation to the Mus bursarius, or pouched 
Rat of Canada: by Samurt L. Mrreutuy, President of 
the Lyceum of Natural History, Professor of Botany and 
Materia Medica, &c. &c. &c. in a letter to J. Miueerr, 
Esq. Corresponding Member of the Society of the Museum 
at the Royal Garden, &c. in Paris ; dated New-York, 
7th October, 1821. 
[Read before the Lyceum of Natural History, October 8, 1821.]} 
My Dear Sir, 
SOMETIME ago, a small quadruped was brought to me 
from the country beyond Lake Superior, which I immedi- 
ately knew to be the Canadian Rat, with large pouches on 
the sides of his neck. 
* We have Professor Green’s memoir on the amphibia of North-America, 
printed in the Journal of the Philadelphia Academy of Natural Sciences, 
(Vol. I. part 2. p. 358.) 
