60 NEW-YORK FAUNA — MOLLUSCA. 
PLANORBIS BICARINATUS. 
PLATE IV. FIG. 63. a. B 
(STATE COLLECTION.) 
Planorbis bicarinatus. Say, Nich. Encyclop. Vol. 4, No. 2, pl. 1, fig. 4 
P. id. Ip. American Conchology, pl. 54, fig. 3. 
P. id, Haupeman, Limniade, p. 3, pl. 1, fig. 1. 
PB; id. Gouxp, Invertebrata of Mass. p. 203, fig. 134. 
Description. Shell orbicular, deeply indented above and beneath. Whorls three, wrinkled 
with minute revolving lines, and strongly carinate on both its sides. Aperture large, abruptly 
vaulted at the carina of the right or upper side. Lip slightly expanded. 
Color. Pale yellow or brownish ; reddish brown within, lighter colored on the carina. 
Animal brownish, dotted with light reddish yellow. Foot tongue-shaped. 
Diameter of the shell, 0°5. Height 0°3. 
Not as numerous as the preceding, but found in sluggish streams and ponds in the State. 
The figure is not at all characteristic of the species. 
PLANORBIS LENTUS. 
PLATE VY. FIG. 80.* a.B. 
(STATE COLLECTION.) 
Planorbis lentus: Say, Am. Conchology, pl. 54, fig. l. 
iP: wt GouLp, Invertebrata of Mass. p. 202, fig: 132 
Description. Whorls three above and four beneath, marked by raised incremental lines . 
above, or on the right side, concave, with a distinct suture ; beneath, not so deep: the whorls 
slightly carinate. Aperture large, oval; its lower margin lying in the plane of the transverse 
diameter of the shell. 
Color. Dark greenish ; lip within dark reddish brown. Animal, dark olivaceous above 
and below : foot oval, minutely dotted with yellowish. 
Size of the preceding. 
This is nearly as common as the preceding, with which it has usually been confounded. 
It is chiefly distinguished from it by the left margin of the lip being in the plane of the trans- 
yerse diameter, whilst in ¢rivolvis it is below it. 
