132 
ORIGIN OF LIFE IN AMERICA 
great scarcity of lizards and the abundance of snakes are 
characteristic features of the north-eastern States of North 
America. But I have not yet alluded to the most remarkable 
feature of the reptilian fauna of that region, as it is not a 
character readily noticeable to the untrained naturalist. It 
is the great wealth of land and fresh-water tortoises. In 
England it is customary to distinguish the marine, paddle- 
limbed kinds of Chelonians as “ turtles,” all others as “ land 
and water tortoises.” In America the term “ turtle ” is 
usually employed quite indiscriminately to true tortoises and 
turtles. In adopting the common American names applied 
to these tortoises, I am only endeavouring to make my 
remarks quite clear to American readers. 
I have had occasion already to refer to one species of 
fresh-water tortoise (p. 51), sometimes called “semi-box” 
turtle (Emys blandingi), and to discuss the peculiar range 
of the genus, which is confined to parts of Canada and the 
northern States in America, and to central and southern 
Europe in the Old World. We possess no fossil remains of 
any members of the genus except from recent geological 
deposits. Although we must assume that a migration has 
taken place either from North America to Europe, or vice 
versa, in more remote times, palaeontology gives us no clue 
as to the origin of Emys. We can only surmise that the 
genus and species of Emys are ancient from the fact that 
the genus Clemmys occurs in the Eocene of North America, 
while Chrysemys has been discovered in the Eocene of 
Europe. Both of these are still living genera of turtles and 
closely allied to Emys. They are classed among what are 
called “ terrapins ” in North America. 
The terrapins are characterised by their broad, flattened 
shell. The hind feet are extensively webbed, and they are 
good swimmers. Perhaps the best known of the terrapins 
is the “diamond-back” (Malacoclemmys centrata)* which 
frequents the salt marshes of the Atlantic coast. It is in 
great favour in the States as an article of diet. The less, 
familiar spotted turtle (Clemmys guttata) is of greater zoo- 
* Ditmars, R. L., “ The Reptile Book.” Siebenrock, F., “ Synopsis 
der Schildkroten.” 
