186 PKOCEKDINGS OF THE MALACOLOGICAL SOCIKTY. 



Paludestrinas. If not, Tryonia would become available for their 

 reception. Of all the aquatic operculates this group is doubtless one 

 of the most iu need of severe critical revision. 



Paludestkina pkotea (Gould). 

 Ammcola protea, Gould, 1855 (syntonic form) ; Ilelania exigua, 

 Conrad, 1855 (syntonic form) ; Hi/drohia Seemani, Frauenfeld, 

 1863; Tryonia clathrata, fStimpson, 1865 (syntonic form); 

 liythinella Heniphilli, Pilsbry, 1890; P. Stokesi, Arnold, 1903. 

 Sliell usually of rather large size but variable in this respect, 

 attenuate-conic, sub-perforate, sutures moderately impressed ; habitat 

 lakes and springs. 



Mexican Province. Utah, Nevada, Columbia, Mojave, and Arizona 

 Systems. Probably present in Klamath, Coast Range, Los Angeles, 

 and Colorado Systems. 



Quaternary : Le Conte Lake beds and San Pedro formation 

 (specimens washed into marine terraces), California; Summer Lake 

 beds, Oregon. 



Pliocene : Kettleman Lake beds, California. 



Palddestrina i.onginqoa (Gould). 

 Amnicola longinqua, Gould, 1855 ; Pomatiopsis intermedia, Tryon, 

 1865 ; Bythinella ' Binneyi, Tryon ', J. G. Cooper, 1888, in ])art ; 

 P. Stearnsiana, Pilsbry, 1899; P. imitator, Pilsbry, 1899; 

 P. ciirta, Arnold, 1903; P. Andersoni, Arnold, 1910. 

 Shell small or of moderate size, elevated-conic, sub-perforate, sutures 

 well impressed ; habitat lakes, mountain streams, and springs, 

 generally in organic mud with Corneocyclas. 



Utah, Nevada, Columbia (locally), Coast llange, Mojave, Los 

 Angeles, Arizona, and Colorado Systems. 



Quaternary: Le Conte Lake beds, calcareous spring deposits of Santa 

 Cruz Mountains, and San Pedro formation (specimens washed into 

 marine terraces), California ; Lahontan Lake beds, Nevada ; Eonneville 

 Lake beds, Utah. Pliocene : Santa Clara, Cache, and Ivettlenum 

 Lake beds, California. 



Genus Fldminicola, Stimpson. 

 Paludina (sp.). Lea, 1838 (P. virens, Lea) ; Amnicola (sp.), Baird, 

 1863 (^A. Hindsii, Baird = P. vireiis, Lea) ; Fltiminicola, Stimpson, 

 1865 (P. Nuttalliana, Lea = P. virens, Lea). 

 Type, Paludina virens, Lea. 



Siib-geuus Heathilla, n. sub-gen. 

 Anculosa (sp.), Haldeman, 1841 {A.fusca, Hald.). 

 Type, Paludina seminalis, Hinds. 



Named in honour of Dr. Harold Heath, under whose guidance 

 a portion of the anatomical studies involved in these pages were made. 

 Sub-genus Fliiminicola, s.s. Shell of moderate size, averaging 

 5 mm. in altitude, elevated-conic, spire decidedly elevated, early 

 volutions slender but expanding rapidly before maturity is reached, 

 whorls inflated, sloping downward and outward, sutures impressed ; 

 habitat streams and springs. 



