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ORIGIN OF LIFE IN AMERICA 
about this blue-tailed slunk is that a species, until recently 
considered absolutely identical with it, is found in Japan, 
being unknown on the mainland of Asia. Some differences 
have now been detected between these two skinks, but they 
are no doubt very closely related to one another. We are con¬ 
fronted, therefore, with the extraordinary problem how to 
account for the occurrence of two species, so nearly akin, 
in localities so distant from one another. It must be clear to 
anyone who is familiar with distributional problems that acci¬ 
dental dispersal within recent times either by man or by 
any other agency is out of the question. This is a case of 
geographical distribution which must be explained by the 
ordinary modes of migration. If it was quite a unique 
instance of such a remarkably discontinuous range, it might 
be a matter of some difficulty to discover a plausible explana¬ 
tion to account for it. But it is by no means the only example 
of such a range. Quite a number of instances are known. A 
still more striking one is that of the so-called ground lizard 
(Lygosoma laterale).* 
The ground lizard, with its minute limbs, thick tail arid 
sluggish movements, reminds one more of a salamander than 
a lizard. It lives, moreover, under the bark of trees or among 
rotten wood, and is thus altogether different in habits from 
the ordinary lizard. Now this peculiar ground lizard occurs 
in identically the same form in North America, in China and 
Japan.f The most searching comparison by the best experts 
has hitherto failed to elicit the slightest difference between 
the Asiatic and this North American ground lizard. 
It is interesting to note that the ground lizard and 
the blue-tailed lizard, both of which exhibit such a remark¬ 
ably East Asiatic relationship, are members of the family 
Scincidae. But, whereas we possess in America over thirty 
species of the genus Eumeces, to which the blue-tailed 
lizard belongs, there are only two American species of 
Lygosoma. We now have to ascertain whether these two 
genera Eumeces and Lygosoma, are of American origin, or 
* Cope, E. D., “ Crocodilians, lizards and snakes of North America,” 
p. 622 . 
f Stejneger, L., “ Herpetology of Japan,” p. 219. 
