SHELES WITKhOUT CANALS 223 
Valvata virens, Tryon, the Green Valve- 
shell, Figure 242, has a turban-shaped shel! 
about 5mm. in diameter. Color, bright 
green; umbilicus wide, operculum circular. 
From Clear Lake, California. 
Paludinélla newcombiana, Hempl., Neweomb’s 
Paludinella, has four distinct, rounded whorls. 
The shell is thin, smooth, and is covered with a 
brown epidermis. Aperture nearly circular, 
length 5mm. These mollusks are amphibious, liv- 
ing in marshes near the sea. From Humboldt 
Bay, Cal. 
Truncatella californica, Pfr., the California 
Looping-snail, lives about salt marshes and upon 
seaweeds and stones. he little eylindrical shell 
is smooth, ight brown in color, with a horny oper- 
culum, and is less than a quarter of an inch in 
length. The surface is smooth, and there are dis- 
tinct sutures between the whorls. 
And now, having studied the shells of the rivers 
and streams, we will go back to old ocean, and 
find a few more families of mollusks awaiting our 
attention. And first we come to a group of shells 
which are somewhat peculiar in shape, having 
internal parts that are quite distinct. 
Figure 248 gives us an inside 
view of the tent-shaped shell of 
Crucibulum spindsum, Sby., the Cup 
and Saucer Limpet. The saucer is 
more or less deep, brownish in color, 
and set on the outside with numer- 
Bigs 2ts ous spines. The cup is small, white, 
Fig. 242 
