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. 253289. 

 t Wallace, A. R, " Island Life," p. 506. 



