HANNIBAL: CALIFOENIAN FBESHWAXER MOLLTJSCA. 



157 



jS'earctic Region ; European Province. 



Quaternary : Loess of eastern States ; post-Glacial deposits of 

 Vancouver and San Juan Islands ; San Pedro formation (specimens 

 washed into marine terraces), alluvial deposits of San Joaquin Valley, 

 Owen Lake beds, play as of Mojave Desert, and Le Conte Lake beds, 

 California. 



Planorbis (Gybaulus) Liebmanni (Dunker). 



Planorhis Liehmanni, Dunker in Martini &. Chemnitz, 1850; 

 P. gracilentiis, Gould, 1855. 



Shell of large size, whorls fairly deep, spire-pit rather broadly 

 concave ; habitat lakes and streams. 



Mexican and Antillean (?) Provinces. Arizona System (locally). 



Le Conte Lake beds, California. 



Probably not the earliest name for this species ; the Mexican 

 Planorbidse are in need of careful revision. 



Planokbis (Gyraulus) filocinctus (Pilsbry & Ferriss). 

 Planorlis filocinctm, Pilsbry & Ferriss, 1906. 



A species of the type of P. alius and P. parvus, but unknown to the 

 writer except from the original diagnosis in the Mollusca of the South 

 Western States, part ii. 

 Arizona System. 



Planorbis (Segjientina) aemigerus (Say). 

 Planorbis armigerus, Say, 1821. 



Shell of moderate size, whorls fairly deep, umbilicus and spire-pit 

 broad, the latter deep, aperture armed, the teeth corresponding to the 

 formula 



\ 



/ 



\ 



\ 



7^ 



habitat sluggish streams and marshes. 

 American Province. Yukon System. 



Planorbis (Segmentina) Mojavensis, n.sp. PL VIII, Fig. 27. 

 Shell large, nautiliform, whorls rounded, deep, not numerous, 

 umbilicus and spire-pit broad, and nearly equal in depth, aperture 

 armed, tlie denticulations corresponding to the formula 



o 

 o 

 o 



\ 



\ 



/ 

 \ 



labitat probably lacustrine. ' 

 Diam. 9-5, alt. 4'5, diam. of aperture 3 mm. 

 Miocene : Eosamond Series, California. 



