XX 



UROCOPTID^E. 



to similarly modified groups in Haiti, Eastern Cuba and 

 Jamaica. Thus, in Jamaica group (1) is represented by 

 Urocoptis s. str., and Bactrocoptis; (2) by Anom,a; (3) by 

 Mychostoma smdApoma; (4) corresponds to Geoscala, etc. 

 In western Cuba, the four groups mentioned, of snails diverse 

 in habits and external form, have so much the same internal 

 structure that their radiation from one form will not be seri- 

 ously questioned; but the representative groups in Jamaica 

 belong to several diverse phyla, as would be expected from 

 its more eventful geological history, including periods of con- 

 nection with the great East Cuba-Haiti island. It seems likely 

 that the vast variety of the Urocoptid fauna in small areas 

 in the Greater Antilles is due to such exigencies and repeated 

 re-adaptations. 



The above considerations are illustrated by the following 

 phylogenetic "tree" of Antillean Urocoptidce, of the two sub- 

 families Urocoptincz and Microceramince. The table does not 

 represent the distribution of the Microceramus gossei group. 



Jamaica. 



Haiti. 



E. Cuba. 



W. Cuba. 



Modern 

 phyla. 



Mesozoic Urocoptinse and Microceraminae. 



GEOLOGICAL AND ZOOGEOGRAPHIC DATA BEARING ON 



UKOCOPTID^:. 



The general sequence of epeirogenic and major orogenic 

 movements of the Antilles has been discussed by a number 



