CYLINDROVERTILLA. 



43 



whorls separate this species from P. dioscoricola; in the last 

 two characters it differs from P. michoacanensis, which also 

 differs by lacking the confluent pitting of the surface. It is 

 much like P. minus in sculpture, except for the low, wide- 

 spaced riblets of mediamericanum; also, the shell is more 

 conic, with a smaller umbilical perforation and more whorls. 

 Bothriopupa breviconus Pils. has a somewhat similarly pitted 

 surface, but it is toothed, a little smaller, with the whorls in- 

 creasing less rapidly, the aperture therefore smaller. 



Genus CYLINDROVERTILLA Boettger. 



Cylindrovertilla BTTG., in v. Martens' Conchologische Mitt- 

 heilungen, i, 1881, p. 62, for Pupa paitensis and P. fabreana. 

 -PILSBRY, Proc. A. N. S. Phila., 1900, pp. 427, 428. 



The shell is sinistral, minute (length 1.6 to 2 mm.), ovate 

 or oblong, tapering towards both ends, smoothish; aperture 

 with long angular and short columellar lamellae, 1 or 2 palatal 

 folds; peristome expanded, thickened within, the termina- 

 tions remote. 



Type C. fabreana (Crosse). 



Distribution: New Caledonia, coasts of Queensland and 

 New South Wales, Australia. 



The chief peculiarity of this genus is that there is no pari- 

 etal lamella, but a strongly developed angular lamella emerg- 

 ing to or towards the termination of the outer lip. This is a 

 highly peculiar condition ; yet from the relation of the lamella 

 to the lip, exactly as in Ptychalaa and Nesopupa, there can 

 be no doubt as to its homology with the angular lamella of 

 other genera. 



Another peculiarity of Cylindrovertilla is that the upper 

 palatal fold is stronger than the lower, and persists when the 

 latter is lost. In most Pupillidae the lower palatal fold is the 

 stronger and more constant. 



The columellar axis is very small, and the columellar 

 lamella extremely short. There is no basal fold in known 

 species, unless it is represented by the basal thickening of the 

 lip-callus in C. fabreana. 



