LIZARDS OF THE EASTERN STATES 
125 
whether they have come to America from some other part 
of the world. Lygosoma laterale is known from eastern 
Mexico in the south-west, and from all the southern and 
eastern States as far north as New Jersey. Altogether fifty 
species of the division of Lygosoma, to which the American 
species belong, have been described.* Five of them live in 
New Zealand, twenty in Australia and the adjacent islands, 
seven in the Pacific Islands, four in the Philippines and 
Borneo, seven in India, two in the Nicobar Islands, one in 
Mauritius, two in West Africa, one in Central America, while 
a single species, as far as we have learnt, is found in China, 
Japan and North America. The wide range of the species in 
North America shows that it has not been introduced. It is 
no doubt indigenous. Yet, to judge from the range of the 
genus Lygosoma, America is certainly not its home. We may 
also safely conclude, from its most discontinuous range, that 
it is of very great antiquity, although quite unknown as a 
fossil. New Zealand, according to Dr. Wallace,f received its 
flora and fauna during the latter part of the Secondary Era, 
and has not since been connected with any mainland. Since 
this view has been widely accepted, it would tend to show 
that the genus Lygosoma was already in existence in 
Mesozoic times, and that it possibly gained its present 
distribution towards the end of the Secondary or early in 
the Tertiary Era. 
The second genus Eumeces may help us in our enquiry 
as to the mode of entry into North America. There are about 
twenty species of Eumeces in North America, ranging from 
Mexico in the south to Minnesota in the north, and New 
Jersey in the east. Considerably over one-half of these inhabit 
the south-western States and Mexico. Certainly the centre 
of distribution in America lies in the south-west. The various 
species seem to have radiated from this centre in all directions 
except the south. The genus must have existed in this south¬ 
western centre for a very long time past, because one species 
peculiar to an island in the Bay of Campeche, another to the 
Island of Bermuda, and still another to southern Florida, are 
* Boulenger, G. A., “ Catalogue of Lizards,” Vol. III., pp. 253—289. 
+ Wallace, A. R., “ Island Life,” p. 506. 
