410 P. S. MARTIN 



viving fauna of four genera is depauperate : Solenodon on Hispaniola 

 and Cuba, Oryzomys (recently extinct?) on Jamaica, Capromys (here 

 to include Geocapromys) on Cuba, the Plana Keys, Jamaica, and the 

 Swan Islands, and the closely related Plagiodontia on Hispaniola. 



Considering the poverty of chiropteran remains elsewhere, the 

 fossil record of the West Indian bats is remarkably good. It has been 

 used to identify relative faunal ages in Jamaica (Koopman and 

 Williams, 1951 ; Williams 1952b). At first glance the presence of two 

 genera of fossil bats now extinct in Jamaica seems to contradict the 

 principle I have noted earlier that late Pleistocene extinction did not 

 affect such animals. Other than commensals and parasites of large 

 herbivores, such as the cowbirds and vampires, we would predict no 

 elimination of life forms among the bats and birds. In theory climatic 

 change during the Wisconsin and earlier Glacial advances altered 

 the ecological opportunities for various genera and changed faunal 

 composition at low latitudes. However, it is my present thesis that 

 generic extinction did not accompany such events. Koopman and 

 Williams' studies make it clear that the local extirpation of bats 

 {Tonatia and Brachyphylla) in Jamaica was accompanied by replace- 

 ment by related genera in the same subfamily. Tonatia and Brachy- 

 phylla survive in Central America and Hispaniola respectively. The 

 Jamaican bat fauna remained rich and bears no resemblance to the 

 annihilation experienced by the terrestrial herbivores. The shift in 

 the species composition of bats may be attributed to climatic change. 



On the other hand, the survival of a rodent, Capromys {Geo- 

 capromys) ingrahami, on the tiny Plana Keys and of C. thoracatus 

 on the Swan Islands, seems a serious violation of the general rule 

 that the smaller the surface the greater the vulnerability to extinc- 

 tion (Fig. 6). The record of Capromys is instructive. C. ingrahami 

 was described in 1891. Closely related fossil populations were sub- 

 sequently found on the larger Bahaman Islands, Crooked, Eleuthera, 

 Long, Great Exuma, Great and Little Abaco. In 1955 Rabb and 

 Hayden (1957) revisited the Plana Keys, collected three specimens 

 of the "cootie" and noted that the island had undergone little change 

 since Ingraham's visit. East Plana Key is a small, rocky islet not 

 more than 50 feet above the ocean, one-half mile wide, four to five 

 miles long and "... entirely without fresh water except in the rainy 

 season, when pools of fresh water may be found in holes in the rocks" 

 (Allen, 1891). In the absence of fresh water it is doubtful that the 



