UROCOPTHLE. xxiii 



islands; but the evidences of great elevation are unsatisfac- 

 tory. It is, however, likely that there was at least transitory 

 connection between Jamaica and Haiti; some forms which 

 had become differentiated in Jamaica then migrating into 

 Haiti, such as Sagda, Stoastoma, possibly Anoma. It may be 

 that there was no all-land Haiti-Jamaican bridge, but an ex- 

 tension of Jamaica eastward in a peninsula, which subse- 

 quently became an island, and then was annexed to Haiti. 

 Something of this sort is needed to account for the absence 

 of many Cuba-Haitian groups in Jamaica. Between Haiti 

 and east Cuba the connection may have been longer, resulting 

 in the homogeneous distribution of Macroceramus, Liguus, 

 the banded Caracolus species, etc. Towards the end of the 

 ensuing depression the rich fossiliferous beds of late Oligocene 

 age at Bowden, Jamaica, and in northern Santo Domingo 

 were deposited at a level not greatly below the present. 



It is likely that during the mid-Oligocene elevation, the 

 Haitian mass included Porto Rico, the Virgin Islands and 

 the islands of the Anguilla bank, the deep channel now inter- 

 vening being of later formation. By this means the Antil- 

 lean portion of the Caribbean fauna Brachypodella, Pine- 

 ria, Pleurodonte, etc. reached these islands. Subsequently, 

 in the Pliocene, the whole Caribbean chain was elevated into 

 a ridge connected with South America, as the presence of 

 large fossil mammals of South American type (Amblyrhiza 

 and Loxomylus) in the Pliocene of Anguilla demonstrates. 

 At this time, Brachypodella extended its range to the con- 

 tinent, migrating thereon westward to Yucatan. 



On zoogeographic grounds, there seems to be but scanty 

 evidence of any direct land-connection between the Greater 

 Antilles and the mainland of Central America or Yucatan 

 during the whole of tertiary time, although the presence of 

 a species of Capromys on Swan Island argues a former great 

 extension of Jamaica westward along the ridge indicated by 

 the Pedro and Rosalind banks, and species of Cepolis, etc., 

 on the Cayman Islands indicate a former extension of Cuba 

 westward from Cabo Cruz, parallel to the Jamaican exten- 

 sion. The investigation of the invertebrates of the Swan and 



