86 NEW-YORK FAUNA — MOLLUSCA. 
the lateral extension of the columella. Color, yellowish green or brownish. Length, 1-0. 
Louisiana. 
P. ponderosa. (Say, Am. Conch. pl. 30. Haxzp. Monog. pl. 4. P. heterostropha, KirTLAND, 
Am. Jour.) Shell reversed, somewhat ventricose, much thickened: spire not much elongated, 
much shorter than the aperture, eroded at tip, but not truncated. Whorls 5, slightly wrinkled 
across; suture profoundly impressed; aperture subovate, more than half the length of the shell; 
pillar-lip with much calcareous deposit, and thickened into a callosity at the superior angle. Color, 
olivaceous. Length, 1:5. Allied to disscisa. Falls of the Ohio. 
P. georgiana. (Lea, Am. Tr. Vol. 5, p. 116, pl. 19, fig. 85.) Shell ventricose, conical, thin, 
smooth: sutures very much impressed. Whorls about 5, convex: aperture nearly round. Color, 
dark horn; aperture white. Length, 1-1. Allicd to vivipara. Darien, Georgia. 
P. vivipara. (Say, Am Conch. pl. 10.) Shell subconic. Whorls 4, rounded; aperture suborbicu- 
sutures impressed. Color, olivaceous, with three reddish brown bands, of which the middle 
lar; 
one is generally smallest; occasionally brownish, with fuscous bands: spire with but two bands. 
South- Carolina. 
P. magnifica. (Conrap, Fr. Water Shells, p. 48, pl. 8, fig. 4.) Shell subovate, ventricose, with two 
spiral bands of prominent tubercles on the body-whorl, and one revolving near the base of each 
whorl of the spire; suture profoundly impressed, margined by an obtuse subnodulous prominent 
line; lines of growth oblique and prominent: obscure spiral striz. Color ; epidermis olive, often 
with purple bands. Alabama. 
P. subpurpurea. (Say, Des. terr. &c. p. 21; Am. Conch. pl. 30, fig. 2.) Shell oblong, subovate, 
subglobular: spire rather obtuse, entire at tip, longer thanthe aperture. Whorls 5, slightly wrinkled 
across, rounded, not very convex; suture not deeply impressed; aperture ovate, orbicular, much 
widest in the middle, less than half the length of the shell; pillar-lip with a calcareous deposit. 
Color, variable, occasionally with traces of obsolete purplish bands. Length, 1-8; greatest 
breadth, 1-8. Wabash. 
P. genicula. (Conran, loc. sup. cit. p. 48, pl. 8, fig. 3. Haxp. pl. 5.) Shell suboval: spire 
slightly elevated. Whorls 4, scalariform; shoulders angulated; apex eroded; aperture rather 
more than half the length of the shell. Epidermis green olive; within bluish. Georgia. 
P. subglobosa. (Say, Jour. Ac. Vol. 5, p. 125.) Shell subglobose. Whorls three and a half, much 
rounded, rapidly enlarging; suture profoundly impressed; aperture subovate; umbilicus very 
narrow, nearly closed by the lip: spire very short, convex. Length, 0°3. Northwes: Territory. 
P. dissimilis. (Say, Nich. Ency. No. 6.) Shell conic. Whorls about 3, with obsolete distant 
wrinkles, and an abrupt acute prominent carinated line, which revolves on the middle of the body- 
whorl, and is concealed on the spire by the suture, occasionally distinct; suture not indented ; aper- 
ture oval, half as long as the shell: columella emarginate, a little flattened at the base. Colo?, 
dark horn or blackish; aperture rufous beneath the carina, and at base and apex. Length, 0-4. 
Pennsylvania. 
P. lapidaria? (Cyctostoma id. Say, Nich. Ency.; Jour. Ac. 1, p. 13.) Shell turreted, subumbi- 
licate. Whorls six, obsoletely wrinkled across; suture impressed; aperture longitudinally ovate- 
orbicular, operculated, rather more than one-third of the shell. Length, 0-2. Under stones, 
Pennsylvania 
