VALLONIA. 



Genus VALLONIA Risso, 1826. 



Vallonia Risso, Hist. Nat. Eur. Merid. iv, p. 101, sole species F^ 

 rosalia. Zurama LEACH in Turton's Man. L. and Frw. Sh. Brit. 

 Is., p. 64, ISBl.Amplexus BROWN, 111. Conch. G. B. 1827 ; Edit. 

 1844, p. 45. Chilostoma FITZ., in part, 1833. Circinaria BECK, 

 Index (in part), p. 23. Glaphyra ALB., Die Hel., 1850, p. 87 (in 

 part). Lucena MOQ.-TAND., Moll. Fr. ii, p. 140, not Oken. See 

 STERKI, Proc. Acad. Nat. Sci., Phila., 1893, p. 234 (monograph of 

 genus, jaws and dentition). ASHFORD, Journ. of Conch, iv, p. 198 

 (dart). LEHMANN, Die lebenden Schneeken u. Muscheln Stettins 

 u. Pommern, p. 90, pi. 11, f. 30 (genitalia, etc.). 



Shell minute, openly and widely umbilicate, depressed, the spire 

 low-convex, consisting of 3-4? whorls, color light and uniform ; 

 surface smooth or ribbed ; periphery rounded ; last whorl usually 

 descending in front. Aperture oblique, circular or short-oval ; 

 peristome continuous or nearly so, expanded or reflexed, often thick' 

 ened within. Type V. pulchella Mull., pi. 55, figs. 31, 32. 



Foot small, short, with no pedal grooves ; edges of sole somewhat 

 crenulated; sole undivided ; eye-peduncles cylindrical, not enlarged 

 distally ; tentacles short ; labial lobes well developed. 



Jaw arcuate, with a slight median projection or none, sculptured 

 with numerous (18 to 25) crowded, low riblets, denticulating the 

 margins (pi. 70, fig. 29, V. pulchella). 



Radula having 23 to 33 teeth in a transverse row. Median teeth 

 decidedly narrower than laterals, tricuspid, the mesocone not half 

 as long as basal-plate, side cusps smaller. Laterals with large 

 square basal plates, the mesocone extending to its edge, ectocone 

 small. Marginal teeth wide and low, multicuspid (pi. 70, fig 38 V- 

 pulchella}. 



Genitalia (pi. 63, figs. 9, 10, V. pulchella, after Lehmann) having 

 the penis short, with terminal retractor; epiphallus short, bearing a 

 flagellum. Dart sack present, single, containing a straight, bladeless 

 dart (fig. 10, x 100). No mucus glands. Duct of spermatheca 

 long, branchless. 



Distribution, North America South to Texas; Japan and middle 

 China to Europe and Atlantic Islands. Fossil the group is known 

 from the lower Eocene ( V. sparnacensis Dh.) ; and in the Miocene 

 several species, lepida Reuss., subpulchella Sandb., occur. 



