220 WEST AMERICAN SHELLS 
Goniobasis occata, Hds., the Harrowed River- 
shell, is found in central California. Its whorls 
are marked by many sharp, roughened, spiral 
ridges or keels. 
Goniobasis acutifilosa, Stearns, 
the Sharp-lined River-shell, Fig- 
ure 238, has the last whorl marked 
with a few spiral keels. It was 
discovered in Eagle Lake, Cal., in 
1877. The figure is rather more 
than twice magnified, but it shows 
the features of the shell 
admirably. 
Gonidbasis rubiginosa, Lea, the 
Pig. 238, x 7) Rusty River-shell, is an Oregon 
species. The earlier whorls have spiral keels, but 
the last one is rounded and has no sculpture. 
Goniobasis nigrina, Lea, the Black 
tiver-shell, Figure 239, has rounded 
whorls without sculpture. Its home is 
in northern California, where it inhabits 
the streams which unite to form the Sac- 
ramento River. There are several varieties, 
including var. draytonu, Lea, and var. circum-- 
lineata, Tryon. Some authorities unite all of these 
smooth, rounded forms under the one species, 
G. bulbosa, the Bulbous River-shell, Gould, which 
has its home in the tributaries of the Columbia 
River. 
In this place properly belongs the description 
of quite a number of minute shells belonging 
largely to the family of the Rissoide, or Risso- 
Fig. 239 
