Synopsis Fre:sh-Wati;r MolIvUSca 



33 



in front ; tentacles long, slender and pointed ; teeth of the radula multicus- 

 pid; central tooth with two basal denticles on each side. Verge small, 

 simple, lunate. 



Type: Melania altilis Lea, fig. 115. Radula, fig. 116. 



Subfamily LYOGYRIN^ Pilsbry, 19 16. 

 Shell minute, conical or subdepressed. Operculum circular, multispiral. 



Key to the genera of Lyogyrincu. 



Shell amnicoliform Lyogynts. 



Shell valvatseform '. (s. g.) Hanffenia. 



Genus LYOGYRUS Gill, 1863. 



. ' Shell very small, spiral, dextral, smooth, umbilicate; globose- 



^1 turbinate or elongate-ovate ; aperture nearly circular ; peritreme 



-p,. continuous, frequently quite separated from the body-whorl. 



^' ^ Operculum corneous, circular, multispiral. 



Rostrum bilobed in front, half as long as the tentacles, which are rather 



stout ; foot auriculated in front ; gill external. Dentition as in Paludestrina, 



basal denticles on rachidian tooth two on each side. 



Type: Valvata pupoidea Gld., fig. 117. 



Genus HORATIA Bourguignat, 1887. 



Shell very small, amnicoliform, thick-shelled, umbilicate, almost smooth ; 

 whorls only 3-4, convex, rapidly increasing, the last large, rounded; suture 

 impressed; aperture very oblique, rounded; lip adherent, straight, sharp; 

 columella thickened, incurved. Operculum corneous, 

 transparent, purple-red, with 3-4 slowly increasing spi- / 

 rals and an almost central nucleus. 



Type: (first species) Horatia klecakiana Bgt. 



Subgenus HAUFFENIA Pollonera, 1898. 



Shell minute, rather thin, valvatseform, widely 

 umbilicate. 



Type: (first species) Horatia tellini Poll. 

 Example: Horatia micra (P. and F.), fig. 118. 



F 



Mff. I], 



