FOSSIL VERTEBRATES IN THE WEST INDIES. 181 



the land areas to or near the borders of the continental shelf in the 

 Pliocene and Pleistocene, and perhaps by some further connections 

 between the greater Antilles. The mammals and chelonians would 

 seem to be practically limited to ocean drift as a method of trans- 

 portation. I have elsewhere discussed the probabilities of this 

 method in its relation to the length of geologic time ; and may add 

 here only that if the estimates made by Barrell of the length of 

 geologic periods are accepted, the chances become from twenty to 

 one hundred times more favorable. For birds and bats, the smaller 

 egg-laying vertebrates, invertebrates and plants, the agency of 

 storms appears to afford the simplest explanation, although wave- 

 borne drift has also doubtless played a part. 



Addendum. 



Dr. Barbour's admirable memoir on the Herpetology of Cuba 

 was published too late to incorporate in the foregoing discussion 

 the very satisfactory solution which he supplies of the alleged Cen- 

 tral American species Crocodihts. moreletii. He shows that this is 

 an error of record, the species being based upon a specimen of C. 

 rhoinbifer from Cuba. The Cuban species is therefore an isolated 

 one in the genus, with no near continental relatives. A study of the 

 series of fossil skulls from Ciego Montero has been undertaken by 

 Dr. C. C. ]\Iook, and will be .published later. 



]Mr. Anthony has suggested in conversation with the writer that 

 the Venezuelan " Procapromys" may like Crocodihis moreletii be 

 an error of record, based upon a specimen erroneously credited to 

 Venezuela, but actually coming from one of the West Indian islands 

 and identical with Geocapromys or Capromys. This, if verified, 

 would clear up the affinities of the Capromys group conformably 

 with the distributional relations of the other rodents, solving a very 

 perplexing problem. 



