346 CUBA CHAP, 



have strayed into the sub-region by three distinct routes : (1) 

 by way of Trinidad, Tobago, and the islands northward ; (2) by 

 a north-easterly extension of Honduras towards Jamaica, form- 

 ing a series of islands of which the Rosalind and Pedro banks 

 are perhaps the remains; (3) by a similar approximation of 

 the peninsula of Yucatan and the western extremity of Cuba. 

 Central America is essentially S. American in its fauna, and the 

 characteristic genera of Antillean operculates which occur on its 

 eastern coasts are sufficient evidence of the previous existence of 

 a land connexion more or less intimate (see map). 



(a) Cuba is by far the richest of the Antilles in land Mollusca, 

 but it must be remembered that it is also much better explored 

 than San Domingo, the only island likely to rival it in point of 

 numbers. It contains in all 658 species, of which 620 are land 

 and 38 fresh-water, the land operculates alone amounting to 252. 



Carnivorous genera form but a small proportion of the whole. 

 There are 18 Grlandina (which belong to the sections Varicella 

 and Boltenia') and 4 Streptostyla^ the occurrence of this latter 

 genus being peculiar to Cuba and Haiti (1 sp.) among the An- 

 tilles, and associating them closely with the mainland of Central 

 America, where Streptostyla is abundant. These two genera 

 alone represent the Agnatha throughout the sub-region. 



There are no less than 84 species of Helix^ belonging to 12 

 sub-genera. Only one of these (JPolymitd) is quite peculiar to 

 Cuba, but of 7 known species of Jeanerettia and 8 of Coryda^ 6 and 

 7 respectively are Cuban. Thelidomus has 15 species (Jamaica 

 3, Porto Rico 3) ; Polydontes has 3, the only other being from 

 Porto Rico ; Hemitrochus has 12 (Jamaica 1, Bahamas 6) ; Cysti- 

 copsis 9 (Jamaica 6) ; Eurycampta 4 (Bahamas 1). 



The Cylindrellidae find their maximum development in Cuba. 

 As many as 34 Macroceramus occur (two-thirds of the known 

 species), and 130 Cylindrella^ some of the latter being most 

 remarkable in form (see Fig. 151, B, p. 247). 



The land operculates belong principally to the families 

 Cyclostomatidae and Helicinidae. Of the former, Cuba is the 

 metropolis of Ctenopoma and Chondropoma^ the former of which 

 includes 30 Cuban species, as compared with 1 from San 

 Domingo and 2 from Jamaica. Megalomastoma (Cyclophoridae) 

 is also Haitian and Porto Rican, but not Jamaican. Blaesospira^ 

 Xenopoma, and Diplopoma are peculiar. The Helicinidae con- 



l! 



