112 HELICOIDBA. 



Genus MICROMPHALIA, Ancey, 1882. 



Shell striated obliquely, or smooth ; spire obtuse, number of 

 whorls moderate ; umbilical perforation narrow ; lip simple, 

 sharp, a little sinuous at the base, with a strong basal tooth at 

 some distance from the margin which is sometimes not devel- 

 oped. New Caledonia. 



Subgenus PLATYSTOMA, Ancey, 1882. 



Spire depressed, but little elevated, whorls few; shell thin, 

 smooth or obliquely striated ; perforation small; aperture large, 

 the lip sharp, edentulous, or having a single tooth at the base. 



Genus RHYTIDA, Albers. I860. 



Shell umbilicated, thin, convexly depressed, undulately striate 

 or rugose ; spire slightly elevated, whorls 4 or 5, somewhat 

 flattened obliquely ; umbilicus rather wide and deep ; aperture 

 oblong-ovate, sometimes dentate within, lip simple, acute, its 

 extremities approaching. 



Animal viviparous ; the lingual teeth rather few, oblique, 

 arcuated ; no central teeth ; no jaw. 



New Zealand, Australia, New Caledonia. 



Genus PARYPHANTA, Albers, 1850. 



Shell rather widely umbilicated, thin, covered by a coriaceous 

 epidermis, enveloping or extending beyond the peristome ; aper- 

 ture oblique, semilunar, peristome simple. 



New Zealand, Australia. 



Genus EL^EA, Button, 1883. 



Shell small, epidermis thin, not involving the peristome ; 

 umbilicus wide ; whorls few, rapidly increasing. New Zealand. 



Genus AEROPE, Albers, 1860. 



Shell with a small, nearly covered umbilicus ; very thin, 

 depressed globose, costulately striate ; spire not prominent, 

 obtuse ; aperture large, semiovate, lip sharp, simple, columellar 

 margin widely reflected over the umbilicus. 



Teeth very long, subulate, arranged in converging rows, and 

 contained in a very large lingual sac. 



A single South African species. 



