62 BULLETIN 181, UNITEiD SrTATEiS N1ATT0i]SI1AjL MUSEfUM 



Subfamily Aperostominae Torre and Bartsch 

 This subfamily is defined on p. 38. 



KEY TO THK GENERA OF WEST INDIAN APEROSTOMINAE 



Basal chondroid plate produced into fimbriations. 



Spire with spiral keels or cords Crocidopoma 



Spire without spiral keels or cords. 



Peristome with a breathing notch Cyclojamaicia 



Peristome without a breathing notch Cyclovendreysia 



Basal chondroid plate not produced into fimbriations. 



Operculum with a strongly elevated calcareous lamella. 



Lamella incurved throughout Cyclopilsbrya 



Lamella not incurved throughout. 



Lamella expanded at free edge Ptychocochlis 



Lamella not expanded at free edge Poteria 



Operculum without a strongly elevated calcareous lamella Aperostoma 



Genus CROCIDOPOMA Shuttleworth 



For definition of GrocidopoTna see p. 39. 



Our knowledge of the anatomy of Groddofoma {Grocidopoma) 

 vortex elevatmti is based upon a very poorly preserved specimen of 

 the animal of this species. It shows a radula having the formula 

 3: 3: 3: 2. The male reproductive system resembles that of 

 Amphicyclotul/us. 



A key to the subgenera of Grocidopoma will be found on p. 39. 



Subgenus Crocidopoma Shuttleworth 



1857. Crocidopoma, Shuttlewokth, Jouru. Conchyl., vol. 5, pp. 271-272. 

 1891. Crocidopoma Crosse, Journ. Conchyl., vol. 39, p. 160. 



In this subgenus the flocculations of the operculum extend very 

 greatly beyond the edge of the calcareous lamella. 



Type: Gyclostoma {Gyclotus) floccdsum Shuttleworth =6'/'0(?i^o- 

 poma {GrocidopoTna) floccoswm (Shuttleworth). 



This subgenus is confined to Hispaniola. 



KEY TO THE SPECIES OF THE SUBGENUS CROCmOPOMA » 



Subsutural spiral keel very strong vortex 



Subsutural spiral keel not very strong. 

 Suture very broadly channeled. 



Shell planorboid casuelense 



Shell depressed-helicoid milleri 



Suture not very broadly channeled. 



Shell helicoid — orcutti 



Shell depressed-helicoid abbotti 



9 0. (C.) floccoaunv (Shuttleworth) is not Included in this key for lack of material for 

 differential comparison with material at hand, none of our specimens satisfying the 

 description thereof. 



