324 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 85 



Axial sculpture not stronger than spiral. 



Axial and spiral sculpture of equal strength. 



Axial ribs strong and distantly spaced oxytremum 



Axial ribs fine and closely spaced edouardi 



Axial and spiral sculpture not of equal strength. 

 Spiral sculpture stronger than axial. 



Summit of the whorls strongly denticulate. 

 Spiral sculpture sublamellar. 



Shell moderately slender . cabrerai 



Shell rather stout perlatum 



Spiral sculpture not sublamellar. 



Spiral sculpture consisting of slender threads. 

 Peristome simple. 



Shell elongate-conic vespertinum 



Shell ovate , jaulense 



Peristome double. 



Peristome sti-ongly auriculate at posterior angle. 

 Postnuclear whorls strongly rounded- nicolasi 

 Postnuclear whorls not strongly rounded. 



appendiculatum 

 Peristome not strongly auricuhite at pcsterior 

 angle. 



Outer peristome of inner lip very broad. 



pfeifEerianum 

 Outer peristome of inner lip not vei-y broad. 

 Denticulations at summit distant. 



poeyanum 

 Denticulations at summit very close. 



laetura 

 Summit of the whorls minutely denticulate. 

 Shell strongly inflated, rotund. 



Peristome simple moestum 



Peristome double. 



Suture channeled , — garcianum 



Suture not channeled. 



Outer peristome rather broadly expanded. 



antonense 



Outer peristome not broadly expanded yucayum 



Shell not strongly inflated, not rotund. 

 Shell elongate-ovate. 



Suture channeled wilcoxi 



Suture not channeled. 



Peristome simple cognatum 



Peristome double. 



Outer peristome auriculate at 



posterior angles , leoni 



Outer peristome not auriculate at posterior 

 angles. 



Whorls strongly rounded pictum 



Whorls almost flattened lembeyi 



