662 ^Y. D. MATTHEW ORIGIN OF THE ANTILLEAX MAMMALS 



The fossil crocodiles have been examined by Dr. Barbour, who informs 

 me that the}' are all referable to Crocodilus rlioinbifev, a species still 

 living on the island of Cuba.^ The origin of this species might be either 

 Xorth or South American; but too little is known of the phylogeny and 

 distribution of the Tertiary Crocodilia for any conclusions to be drawn 

 as to the time or method of its arrival. 



The fossil chelonians have not been carefully studied, but they include 

 two species — one a giant tortoise, Testudo cubensis Leidy, which, like 

 the giant tortoises of the Galapagos and Indian Ocean islands, has the 

 carapace much thinned Out, so that the plates are apparently more or less 

 discontinuous. There is one North American Pliocene species, T. per- 

 tenuis Cope, from Texas which has a remarkably thin carapace, but 

 apparently not discontinuous. The precise sigTiificance of this species in 

 the paleogeographic problem must also await more careful study. The 

 genus Testudo occurs sparingly in South America, and is recorded as a 

 fossil in the Pliocene and Pleistocene formations — not earlier, so far as 

 I know. On the other hand, species of Testudo are the most abundant 

 of fossils in the Oligocene to Pliocene formations of North America; in 

 the Pleistocene and Recent their range is restricted to the Southern States 

 and Mexico. The indications point, therefore, preferably to North Amer- 

 ican origin for this Cuban tortoise, although not decisively. 



-The second fossil chelonian is one of the Emydid?e, or marsh -turtles; 

 it appears to be a species of Graphemys. probably the same as the still 

 existing Cuban species, which is said to be a close ally of G. scripta of the 

 Southeastern States. Whether the two are specifically distinct has been 

 questioned. The discovery of this species (if it be the same) fossil in the 

 Ciego Montero locality removes any doubt as to its being indigenous to 

 the island, as it carries it back into the Pleistocene, and probably to a 

 time before the arrival of man. Its close relationship with G. scripta and 

 limitation to the western islands, Cuba and Haiti, is a strong indication 

 of its having come from Florida, and the time of its arrival probably 

 would be not earlier than Pleistocene or at most late Pliocene. 



Summary of Affinities and probable Origin of the vertebrate 



Groups 



Summing up the indicated sources of the fossil and recent vertebrate 

 fauna, we find it to be as follows : 



* Leidy's Crocoflilus pristinus (1868, 1. c.) was based upon a vertebra not distinguished 

 from C. rhomMfer. The skulls obtained by La Torre and Brown represent, in Doctor 

 Barbour's opinion, a series of growth stages of the modern species, the largest much 

 exceeding any modern specimens. Part of a skeleton associated with one of the largest 

 skulls equals or exceeds Leidys type of pristinus in size. 



