VALLONIA. 249 



Circumboreal . Europe, eastern and northern Asia, northern Africa, 

 the Azores and Madeira, greater part of North America ; also Australia 

 and Mauritius (introduced) (? Pacific slope, and eastern Asia.) 



Hel. pulchella MULL., Verm. Hist. II, 1774, p. 30, and of authors! 

 Hel. paludosa DA COSTA, 1780. Hel. crystallina DILLW., 1817. 

 Hel. pulchella var. Icevigata MOQ.-TAND., 1855. Hel. minuta SAY, 

 Journ.Acad.Phila.,1817, p. 123, and Nicholson's Enc. Ed. 3, 1819. 

 Vallonia minuta MORSE, Pulmonif. Me., 1864, p. 21 (? part). 

 TRYON, Am. Journ. Conch. Ill, 1867, p. 36 (?) Vallonia pulchella 

 W. G. BINNEY, Terr. Moll. V, p. 344; Man Am. Land Shells, 

 1885, p. 77. 



The last whorl is slightly ascending or descending in front, in a 

 good part of the specimens. Sometimes the shell is whitish, milky- 

 opaque, in living examples ; this seems to be a local variation, as all 

 the specimens in certain places show this peculiarity. The size of 

 the shell varies from 2*1 to 2*7 greater diam., 2'4 being the average. 



Jaw rather strongly curved, with obtuse ends ; no median projec- 

 tion on the cutting edge, which is denticulated corresponding to the 

 10-20 rather sharp, longitudinal ribs, quite irregular in size, course, 

 and distribution, but wanting at the side ends of the jaw. The 

 radula has 65-68 transverse rows of 27 teeth ; of the five laterals 

 the fifth has a small plate and the ectodont double pointed. 



For the question concerning the identity of V. minuta Say, see 

 under V. excentrica. 



Var. ENNIENSIS Gredler. 



A form with strong, rib-like striae, but without membranous ribs, 

 the other characters as in the type. ( Gredler, Tirol's Conchylien, 

 1856.) 



Neumarkt Hall and Botzen in Tirol ; Grasse, France. 



Var. PERSICA Rosen. 



Differs from the type in having the last whorl descending to the 

 aperture ; the latter with widely expanded, flat [piano] peristome. 

 (Rosen, Nachr. Bl. D. Mal.Ges. 1892, p. 123.) 



Schamhala, Prov. Chorassan, Persia. 



This may be a form distinct from pulchella. 



V. EXCENTRICA Sterki, n. sp. PI. 32, figs. 6, 7, 8, 9. 



Moderately umbilicated, the umbilicus elongate, rapidly widening 

 for the last i whorl; slightly convex above ; pale horn colored, trans- 



