HAJfNIBAL: CALIFORNIAN FRESHWATER MOLLUSCA. 161 



Sliell rather small, finely striate, whorls deep and of moderate size, 

 umbilicus and spire-pit prominently funicular, the former particularly 

 so, superior and inferior peripheries pronouncedly carinate, aperture 

 expanded in adult ; habitat lakes and quiet streams. 



American Province. Columbia and Fraser Systems. 



Quaternary : Loess of eastern States. 



Helisoma (Perrinilla) Pabloana (J. G. Cooper). 

 Planorhis Pahlomius, J. G. Cooper, 1894. 



Shell small, coarsely striate, whorls not deep and rather small, 

 umbilical carina nearly obsolete, sub-marginal, the umbilicus unevenly 

 concave, spire-pit rather broad for group, aperture but slightly 

 expanded; habitat apparently lacustrine. 



Miocene : Contra Costa Lake beds, California. 



A small inconspicuous species lacking the evenly dished umbilicus 

 of Cordillerana. The type was crushed flat, and alone would hardly 

 be sufficient to distinguish the species if still in existence. Several 

 fairly preserved specimens from the vicinitj' of the original locality 

 permit a diagnosis, however. 



Helisoma (Perrinilla) Cordillerana, n.sp. PI. IV, Fig. 34 ; 

 PI. VI, Fig. 16. 



Shell of considerable size, whorls large, somewhat compressed, and 

 strongly ultra-sinistral, the umbilicus barely concave, superior and 

 inferior peripheries subangular in young stages, becoming rounded in 

 adult, growth-striae strong, spiral striae occasionally ])reserved, aperture 

 expanded somewhat in adult; habitat apparentlj" lacustrine. 



Diam. 22, alt. 9, diam. of aperture 12 mm. 



Eocene : Truckee Lake beds, Nevada. 



Hill near Hawthorne on the Belmont stage road (types) ; near 

 Hawthorne (probably same locality) (H. W. Turner); one mile 

 south-east of coal-mine, Silver Peak llange (S. A. Knapp, H. W. 

 Turner); \h miles south-east of coal-mine (H. W. Turner); hill 

 immediately back of coal-mine (H. W. Turner) ; 7-7 km. north-east 

 of Emigi'ant Gap, and 8*6 km. south-east of coal-mine, Silver Peak 

 Range (H. W. Turner). 



Possiblj' co-specific with Planorhis Utahensis, Meek, from the same 

 horizon in the Rocky Mountains. The species belongs to this group, 

 but the figures are not characteristic and no specimens are available. 



Family POMPHOLIGID^, Dall, 1866. 



Shell of small or moderate size, velutiniform or sub-planorbiform, 

 dextral, showing fine spiral and growth stria3, aperture ovate or ovate- 

 quadrate, columella simple, imperforate, or umbilicate ; animal sinistral, 

 hermaphroditic, tentacles clavate, buccal plate sub-cordiform, lateral 

 jaws absent, foot quadrate-elliptical ; habitat lakes and clear streams. 



The genus Pompholi/x, the sole known representative of this family 

 and a strictly Californian group, contains four Cenozoic species which 

 differ rather widely in superficial appearance, and with tlie exception 

 of the recently described P. Sanctceclarcc have served as the types of 



