THE DIFFERENCES BETWEEN THE GEO- 
GRAPHIC TURTLES {Mcdacodemmys geo- 
graphicus and M. lesueuri) . 
PLATE II. 
BY H. GARMAN. 
Early writers on our lierpetology were not fortunate in 
their treatment of these turtles. Some did not recognize 
them as distinct, others considered them varieties of one 
species, while those who admitted their distinctness gener- 
ally failed to make clear the differences between them. 
Most recent authors seem to have made use of characters 
furnished hy early writers, and the result is that we have 
few descriptions which by themselves will enable us to say 
positively whether examples Avhich come to our hands rep- 
resent M. lesueuri, or its relative, M. geographicus. 
The original description of M. geograjjhicus (Le Sucnr, 
Journ. Acad. Nat. Sci. Phil., i, 86, 1818) gives no char- 
acters by means of which this species can be distinguished 
from the later-described M. lesueuri. But in the accom- 
panying figure {ibid. pi. v), Le Sueur shows the charac- 
teristic large head, massive jaw and a peculiar tympanal 
stripe. After publishing this description, Le Sueur be- 
came acquainted with M. lesueuri, and the elder lie Conte, 
writing some time later, stated that he seemed to consider 
it the one he had described as Tesludo geogrcq^hica. How- 
ever this ma}^ have been, his figure in the Journal of the 
Philadelphia Academy will not permit us to believe that 
Le Sueur had anything in mind but M. geogrcqjhicus when 
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