132 ORIGIN OF LIFE IN AMEEICA 



great scarcity of lizards and thie aTjundanoe of snakes are 

 characteristic features of the north-eastern States of North 

 America. But I have not yet alluded to the most remarka,Me 

 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 Cheloniains 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 pf 

 any members of the genu3 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, E. L., " The Eeptile Book." Siebenrook, F., " Synopsis 

 der SoMldkroten." 



