FOSSIL VERTEBRATES IN THE WEST INDIES. 171 



older Tertiary marine limestones of Jamaica. It is distantly related 

 to the manatees, but it throws no light upon the problems here con- 

 sidered, and may be passed over without discussion. 



Review of the Fauna an now known. Its incomplete and 



INSULAR character. UNIFORMITY THROUGHOUT THE LARGER 



ISLANDS. Probable derivation of the several groups. 

 Methods of colonization. 



So much for the new discoveries. We may now review the 

 fauna as a whole, living and extinct, and consider its general char- 

 acter and what bearing it has upon the past history of the islands. 

 I shall deal principally with the mammals, partly because I am best 

 acquainted with them, partly because the new discoveries are chiefly 

 in this group, and partly because I think they afiford the best evi- 

 dence upon certain critical points. 



The most obvious features to me in the mammal fauna are its 

 incompleteness and insular character. There are no perissodactyls, 

 no artiodactyls, no proboscidians, no carnivora, no primates, no mar- 

 supials, no rodents except three groups of the Hystricomorphs 

 which are an especially South American group, no insectivores save 

 for two types which have very remote affinities to any living groups, 

 none of the various types of edentata, except a single group of 

 ground sloths. Certainly this poverty of mammalian fauna is not 

 to be explained by scantiness of material. We have very large col- 

 lections, many hundreds of jaws and a due proportion of other 

 bones, from two types of deposit, a cave and a spring fauna. Cor- 

 respondingly large collections from cave or spring faunas in North 

 America or South America yield very different results. Compared 

 with the Port Kennedy, Conard Fissure or the California cave 

 faunas, or those described by Lund and Winge from Brazil, the 

 contrast is very striking. Spring faunas may be less varied, but 

 whatever else is absent the larger ungulates are sure to be found in 

 such situations. 



The whole Antillean mammal fauna consists of only six types 

 or groups of sub-family rank at most, as follows : 



1. Ground sloths allied to Megalonyx — 5 genera. 



2. Rodents of the Capromys group — 4 genera. 



