562 REPORT OF NATIONAL MUSEUM, 1902. 



dentl}^ introduced by man and belonging to widely different South 

 American species. No LeptodactyJm or related form is found in 

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

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

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

 of Tehuantepec." 1 know of absolutely no parallel to this extraordi- 

 nary range, which is inexplicable on ordinary distributional grounds, 

 for certainl}^ it w^ould transgress the boundaries of the probable to 

 suppose either that this species had once covered the whole country 

 between Tehuantepec and the Virgin Islands and l^ecome 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 yet to be discovered in these islands, but Z. 

 aXbllahrk is not likely to be one of them, for it is one of the conunon- 

 est, most obtrusive, and most easilj^ caught batrachians wherever it 

 occurs. In suggesting accidental introduction by 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 Virgm 

 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, Hemidactylvs mahouia and Lejjtodactylus alhi- 

 labrls, 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 closel}" allied to the types characteristic of northeastern 

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

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

 mainland opposite. 



The Amphisbgenians, judging from the present distribution of the 

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

 {TypJdojJs) almost certainly did so. 



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



