Snails of this genus are very small with narrow shells. Females brood young within the genital tract. Species usually live in
springs. The genus is differentiated from others by the structure of the male and female reproductive systems.[4]
Most of these snails occur in western North America, especially the
Chihuahuan Desert. There are also species known in
Florida and
Guatemala.[4]
Stimpson, W. (1865). Researches upon the Hydrobiinae and allied forms chiefly made upon materials in the museum of the Smithsonian Institution. Smithsonian Miscellaneous Collections 7
(201): 1-59.
page 48.
Thompson F.G. (2011) An annotated checklist and bibliography of the land and freshwater snails of México and central America. Florida Museum of Natural History, Bulletin 50(1): 1-299.