SNAKES OF THE EASTERN STATES 
127 
Eocene deposits of France and England, we have no reason 
to doubt that the family has originated in America. The 
Cretaceous genera Iguanavus and Chamops from Wyoming, 
have always been considered as belonging to the Iguanidae. 
Since the family scarcely enters eastern America even at the 
present day, the western States must always have been its 
headquarters. How the dispersal from the American con¬ 
tinent to the Fiji Islands was effected is another problem 
which I defer to a later discussion. 
As for the genus Sceloporus, to which the swift (S. undu- 
latus) belongs, almost all the species inhabit Mexico, that 
country forming the centre of distribution. From there the 
genus ranges as far south as Nicaragua,. One species occurs 
in the western States, while the single northern species, 
Sceloporus undulatus, ranges from Guatemala to the eastern 
States. Both the nearest relations of this genus, Phrynosoma 
and Uta, have their headquarters in the south-western States 
and Mexico. We possess, consequently, satisfactory evidence, 
both from its recent as well as its fossil distribution, that 
the family Iguanidae is of North American origin, and that 
the latter can be traced to the end of the Mesozoic Era. 
In spite of the occurrence of these three species of lizards 
in some of the north-eastern States, these reptiles certainly 
are scarce in the east. It is not so with the snakes. No less 
than twenty-three different kinds have been observed in the 
vicinity of New York,* whereas in the whole of France there 
are only about half that number. The eastern States of 
America are, in fact, remarkably rich in snakes. Snakes have 
even penetrated to the eastern islands, for several species, in¬ 
cluding the dreaded rattlesnake, occur in Long Island. 
The commonest of these eastern and probably of all the 
American snakes, is the garter-snake (Thamnophis or Eutenia 
sirtalis). It is abundant from southern Canada to Florida, 
and I have met with it even on the edge of the White Moun¬ 
tains plateau at a height of 5,000 feet. Very closely allied 
to, and scarcely distinct from the genus Tropidonotus, the 
garter-snakes (Thamnophis) form a most troublesome group 
* Eckel, E. C., and F. C. Paulmier, “New York Reptiles,” p. 356— 
388. 
