32 FOSSIL TURTLES OF NORTH AMERICA. 
groups of turtles combined. Accepting the genera and species as described by Mr. 
George A. Boulenger in his Catalogue of the Chelonians, there are 30 genera of 
Cryptodira with 140 species; 21 genera of Pleurodira, with 24 species; 6 genera of 
Trionychidz, with 24 species. The headquarters of the superfamily is North America. 
RR Sp TS {, (ee, SN AAT” 
ey ee > baat, Fa on “A ) NS at PD fee J 
is My @ a » HK Bs po 4 4 
p ) 
‘ sie es > wt 
EQUATOR yey SS — — 
|p ___ ce  et NGsy 
Fic. 11.—Map showing geographical distribution of the Chelydrida. Portions of the western 
hemisphere and the island of New Guinea. 
Fig. 11 shows the distribution of the Chelydride. The northern limits of the 
family are somewhat uncertain. The same species, Chelydra serpentina, that occurs 
in Canada, is found also in Ecuador, South America. Until recently it has been 
supposed that the members of this family are confined to the New World; but J. 
Douglas Ogilby has reported (Proc. Roy. Soc., Queensland, x1x, 1905, p. 11) the 
discovery of a new genus and species, “Devista “mythodes, i in the Fly river, New 
Guinea, the river that has furnisht likewise the remarkable turtle Carettochelys. 
The New Guinea snapper has a length of 860 mm., the carapace being 330 mm. 
long. This distribution of the snappers is even more remarkable than that of the 
camels and tapirs. 
\ \ / 
YN Ree 
Si Sy een a 
N “ y w 8 
Sea 
Fic. 12.—Map showing distribution of the Dermatemydide. 
Fig. 12 displays the distribution of the Dermatemydidz. This is one of the 
decadent families of the order, for it abounded in genera and species in the Upper 
Cretaceous of North America and still existed in reduced numbers during the Ter- 
tiary. The family, now consisting of three genera and four species, is confined to 
portions of Mexico and Central America. 
As seen from fig. 13, the Emydidz have a wide distribution, occupying all the 
habitable portions of North America, South America, Europe, rete and most of the 
