354 



CENTRAL AMERICA 



The land operciilates are but scanty. Tomocydus and Amjjhi- 

 cyclotus are peculiar, and Schasicheila, a form of Helicina, occurs 

 elsewhere only in the Bahamas. Geres (see Fig. 18, C, p. 21) and 

 Proserpinella, two remarkable forms of non-operculate Helicinidae 

 (compare the Chinese Hcudeia), are c[uite peculiar. Pachychilus, 

 one of the characteristic fresh-water genera, belongs to the 8. 

 American (Melaniidae) type, not to the N. American (Pleuro- 

 ceridae). Among the fresh-water Pulmonata, the Aplecta are 

 remarkable for their great size and beauty. In the accompany- 

 ing table " Mexico " is to be taken as including the region from 

 the United States border up to and including the isthmus of 

 Tehuantepec, and " Central America " as the whole region soutli 

 of that point. 



Land Mollusca of Central America 



(3) The Colombian Sub -region includes Colombia, New 

 Grenada, Venezuela, Guiana, Ecuador, Peru, and Bolivia. It has 



