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, forming 

 a series of islands of which the Eosalind 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 fhe 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 3 8 fresh- water, the land operculates alone amounting to 25 2. 



Carnivorous genera form but a small proportion of the whole. 

 There are 18 Glandina (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 

 Antilles, 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 {Polymita) 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 Eico 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 3 Cuban species, as compared with 1 from San 

 Domingo and 2 from Jamaica. Megalomastoma (Cyclophoridae) 

 is also Haitian and Porto Eican, but not Jamaican. Blaesospira, 

 Xenopoma, and Dip)lopoma are peculiar. The Helicinidae con- 



