THE EDENTATA 661 



lated to the North American genus Megalonyx to be placed in the same 

 subfamily, they are quite evidently not descended from it, but con- 

 temporaneous specializations from the primitive Megalonychida} of the 

 South American Miocene, as represented in the Santa Cruz fauna. Among 

 the known genera of this fauna there is only one, Eucholoeops (including 

 Megalonycliotherium) , which can be regarded as ancestral either to the 

 Cuban ground-sloths or to Megalonyx. The others all have the canini- 

 form teeth much reduced or vestigial and in series with the cheek teeth. 

 To the best of my judgment, the anatomical evidence is not decisive as to 

 whether the five Antillean genera are descended from one or from two 

 or more nearly allied Upper Miocene or Lower Pliocene genera, but leads 

 to the conclusion that the common ancestor or ancestors was very close 

 to or identical with the Upper Miocene ancestor of Megalonyx, and was 

 either the genus Eucholoeops or one or more genera closely allied thereto. 

 The Antillean genera represent, therefore, only the megalonychine divi- 

 sion of the Megalonychidae. The other families of ground-sloths — Mylo- 

 dontidse, Scelidotheridse, and Megatheriidse — are not found; nor are there 

 any armadillos, glyptodonts, or anteaters. 



BATS AND BIRDS 



In addition to the terrestrial mammals, bats are numerous in the cave 

 deposits, and a number of birds, lizards, crocodiles, and turtles have be.eu 

 found at the Ciego Montero locality and elsewhere. 



Concerning the bats, there is very little to say. Most of them are 

 nearly allied to or identical with species now living on the islands. The 

 Antillean bats include a number of peculiar genera, besides others com- 

 mon to the continental parts of tropical America. Their relations are 

 much the same as those of the birds, and in either case it is obvious that 

 the intervening seas would act as a hindrance to migration, but not as an 

 absolute barrier, and would be more of a hindrance in some groups than 

 in others. The result would be the presence of a number of peculiar 

 types, preserved by relative isolation and specialized in adaptation to the 

 peculiarities of their habitat, along with other widely ranging forms 

 closely allied to or identical with those of the mainland. The distribu- 

 tion of the birds has been carefully studied by Chapman and others. 



REPTILES 



The distribution of the lizards has been recently studied by Dr. Thomas 

 Barbour, and his conclusions as to the paleogeography are sharply at 

 variance with mine, owing to different methods of interpreting the data. 

 I shall not take this part of the problem up at present. 



