562 REPORT OF NATIONAL MUSEUM, 1902. 



dently introduced by man and belonging to widely different South 

 American species. No Leptodactylus or related form is found in 

 Haiti, Cuba, or Jamaica. But the most curious feature is that a frog 

 which neither Dr. Boulanger nor I can distinguish from L. albilabris, 

 is a native of southern Mexico, State of Vera Cruz, and the Isthmus 

 of Tehuan tepee. a I know of absolutely no parallel to this extraordi- 

 nary range, which is inexplicable on ordinary distributional grounds, 

 for certainly it would transgress the boundaries of the probable to 

 suppose either that this species had once covered the whole countiy 

 between Tehuantepec and the Virgin Islands and become extinct in 

 the intermediate territory, or that there had at any time been a direct 

 connection between the localities mentioned to the exclusion of the 

 large Antilles. Nor can it for a moment be supposed that the species 

 exists in the latter without having attracted attention. No doubt 

 there are many species }^et to be discovered in these islands, but L. 

 cdb'dabris is not likely to be one of them, for it is one of the common- 

 est, most obtrusive, and most easil} 7 caught batrachians wherever it 

 occurs. In suggesting accidental introduction b^- man I am fully 

 aware that this explanation does not at first appear plausible, as there 

 does not seem to be or to have been any direct route of communication 

 between southern Mexico or Yucatan and Porto Rico or the Virgin 

 Islands, but I offer it as the only possibility I can think of. The 

 wrecking of a vessel with a cargo of logwood or mahogany a hundred 

 years or more ago might account for this remarkable distribution. 



Leaving, then, out of consideration the two species whose introduc- 

 tion we ascribe to man, Hemidactyhis mahouia and Leptodactylus albi- 

 labris, the herpetological fauna of Porto Rico falls into two groups, 

 namely, the species which have in all probability originally extended 

 their range from northeastern South America and those whose ances- 

 tors came from the west, primarily from the present mainland of Cen- 

 tral America, and secondarily from the other Great Antilles. 



Comparatively few, probably not more than five of the genera 

 inhabiting Porto Rico, point toward South America. 



Ameiva is probably of southern origin. The West Indian members 

 of this genus form several minor but fairly well circumscribed groups, 

 indicating that they originated from a secondary evolutional center 

 located in the archipelago. Nevertheless, on the whole they appear 

 to be more closely allied to the types characteristic of northeastern 

 South America than to the Central American forms, those found in 

 Cuba and Jamaica being most divergent, perhaps, from those of the 

 mainland opposite. 



The Amphisbamians, judging from the present distribution of the 

 genus, probably also entered from the south, and the blind snakes 

 {Typhlops) almost certainty did so. 



"Also possibly Yucatan. Ives, Proc. Phila. Acad., 1891, p. 461. 



