MID-ATLANTIC LAND BEIDGE 281 



of North America. I explained this by the supposition that 

 the widespread submergence of the Antilles destroyed most of 

 the immigrants from Europe. It ought not to have affected 

 the emigrants to Europe from the Antilles to the same extent, 

 I mean those forms which spread from the Antillean centre, 

 because they would have had more time to adapt themselves 

 to the more elevated regions in the West Indies, and would' 

 thus have had more chance of .surviving the submergence 

 which did not entirely cover the islands. 



One of the most noteworthy examples of that kind, though 

 not a very conspicuous onq, is the newt Spelerpes. [ alluded 

 to its range in North America on several occasions (pp.137 

 138 and p. 221), pointing out that its headquarters were in 

 Mexico, while a single species had succeeded in reaching the 

 Mediterranean region. We may assume, therefore, that 

 certain members of the old American Spelerpes stock 

 emigrated, in early Tertiary or even in Mesozoic times, by | 

 means of the trans -Atlantic land bridge, that extended from j 

 the Antilles to a land area which covered part of the western 

 Mediterranean (Fig. 14). That Spelerpes long ago existed all 

 over the Antilles is indicated by the fact that a single species 

 (Spelerpes infuscatus) still inhabits the island of Haiti. 



Another instance I alluded to (p. 173) in support of ? 

 the mid-Atlantic land bridge theory, is the glass-snake j 

 family (Anguidae). The genus' Ophisaurus, which is found 

 in the Mediterranean region, does not occur on the Antilles, 

 but several species are known from the mainland of North 

 America. The genus Anguis is quite confined to Europe, 

 western Asia and north Africa. On the other hand, numerous 

 relations live in the West Indies. Sauresia and Panolopus are 

 confined to Haiti, whereas Celestus (Diploglossus) inhabits 

 Portorico, Haiti, Jamaica, Cuba, Central America, Mexico 

 and northern South America. The headquarters of the 

 Anguidae certainly are in the West Indies and Central 

 America, and it is from there that they must have spread to 

 Europe and beyond, as far as the Himalayas, when a land 

 bridge across the Atlantic permitted them to do so. 



Let us now return to the investigation of the geological 

 history of the Antillean area. Among the vertebrates, the 

 mammals perhaps are of the greatest importance, in so far 



