
MOLLUSCS, VERMES AND H YDROZOA 

Somatocyrus. These small snails are quite generally distributed, 
and on account of their size harmless and inconspicuous in the aquarium. 
They are slothful in their habits and hibernate in cold water. The shells 
are pretty and of fine form. 
S. altilis, Fig. 154, has a 34 to ,4 inch long, smooth, thick, subglobose 
pale light-green or horn-colored shell of four whorls, with a sharp suture, 
short spire, nearly round- 
ed aperture and regularly 
ovate operculum. The 
body is brownish-grey, 
the tentacles long and 
somewhat slender, and : 
the eyes a bright bluish- FIG. 154. Somatogyrus aitilus. Enlarged. 
black. It is quite generally distributed in the eastern section of the United 
States and has been found in the Potomac at Washington, and in both the 
Delaware and Schuylkill rivers. Also occurs in cold water ponds in the 
Middle States generally. 
S. subglobosus, Fig. 155, has a 14 to 3¢ inch long obliquely transverse 
subglobose solid polished yellowish-green shell of four whorls,.an impressed 
suture, a short spire and an oblique white aperture. The body is yellow- 
ish-brown or grey and 
the tentacles brown. It 

is not common to the 
Eastern and Middle but 
occurs in the Southern 
States, principally in 
South Carolina, but is 
occasionally met with in 
Virginia and Maryland and at Washington, D. C. 
AmnicoLa. These tiny snails are principally mentioned as they con- 
stitute a numerous genus, the Hydrobide. They have thin ovate conical 
shells with acute spires, small oblique, rounded ovate apertures and horny 
opercule; are widely distributed and occur abundantly in many localities. 
A. limosa, Fig. 156, has a conical very convex yellowish-brown 
slightly wrinkled 1% inch long shell tinted with grey, of five or six whorls, 
with deeply impressed su- 
tures’ “Fhe “body whorl 
takes up about one-half the 
length of the shell. The 
body is brown and the ten- 
tacles of a lighter color. It 

FIG. 155. Somatogyrus subglobosus. Enlarged. 
[ 
. 156. Amnicula limosa. Enlarged. 

