86 BULLETIN 160, UNITED STATES NATIONAL MUSEUM 



would separate average individuals on the mainland from those on 

 the islands. These distinctions, however, are qualified by the remark 

 that there are individuals that are so similar that no distinguishing 

 characters are apparent. The series of specimens from St. Thomas 

 Island, West Indies, and from the mainland of Mexico available for 

 comparison is not very large, but nevertheless the distinctions made 

 by Noble fail to separate these lots into two categories. The speci- 

 mens from St. Thomas Island used in these comparisons do not have 

 the skin on the tibia any more noticeably studded with numerous 

 sharp-pointed tubercles than those from the mainland, and the throat 

 is stippled with brown around the edges. Furthermore, many of 

 the mainland specimens have light-margined brown spots on the upper- 

 parts, and the color pattern is quite if not almost identical with the 

 island specimens. It is true, however, that specimens from St. 

 Thomas Island are somewhat larger than any of those collected in 

 Mexico, but otherwise they are inseparable from the latter. 



In commenting upon the relations and origin of the Porto Rican 

 herpetological fauna. Doctor Stejneger ^■^ says: 



The status of the frog, Leptodadylus albilabris, is quite different from that of 

 the other species of the fauna. In the Antilles it is restricted to the Virgin 

 Islands, St. Croix, Vieques, and Porto Rico. There is apparently no indigenous 

 species of the genus in the Caribbean chain, the other two which occur in various 

 islands being evidently introduced by man and belonging to widely different 

 South American species. No Leptodadylus or related form is found in Haiti, 

 Cuba, or Jamaica. But the most curious feature is that a frog w^hich neither 

 Dr. Boulenger nor I can distinguish from L. albilabris, is a native of southern 

 Mexico, State of Vera Cruz, and the Isthmus of Tehuantepec. I know of abso- 

 lutely no parallel to this extraordinary 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 country 

 between Tehuantepec and the Virgin Islands and become extinct in the interme- 

 diate 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 L. albilabris is not likely to be one of them, for it is one of the commonest, 

 most obtrusive, and most easily 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 Virgin Islands, but I offer it as the only possibility I can 

 think of. The wrecking of a vessel with a cargo of logw'ood or mahogany a hun- 

 dred years or more ago might account for this remarkable distribution. 



Doctor Barbour '^^ is inclined to question this assumption and 

 contends that the occurrence of this species in the West Indies is not 

 traceable to any agency of man. He says: 



s< stejneger, L., The herpetology of Porto Rico. Ann. Kep. U. S. Nat. Mus. for 1902, pp. 661, 662, 1904. 

 8' Barbour, T., A contribution to the zoogeography of the West Indies, with special reference to amphib- 

 ians and reptiles. Mem. Mus. Comp. Zool., vol. 44, no. 2, p. 253, Mar., 1914. 



