86 NEW-YORK FAUNA MOLLUSCA. 



the lateral extension of the columella. Color, yellowisli green or brownish. Length, 1 '0. 

 Louisiana. 



P. ponderosa. (Say, Am. Conch, pi. 30. Hald. Monog-. pi. 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 -o. Allied to disscisa. Falls of the Ohio. 



P. georgiana. (Lea, Am. Tr. Vol. 5, p. 116, pi. 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. Allied to vivipara. Darien. Georgia. 



p. vivipara. (Say, Am Conch, pi. 10.) Shell subconic. Whorls 4, rounded; aperture suborbicu- 

 lar; sutures impressed. Color, olivaceous, with three reddish bromi bands, of which the middle 

 one is generally smallest; occasionally brownish, with fuscous bands : spire with but two bands. 

 South-Carolina. 



P. magnijica. (Conrad, Fr. Water Shells, p. 48, pi. 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 stris. 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, 

 •?ubglobular : spire rather obtuse, entire at tip, longer than the 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 -S. Wabash. 



P. genicula. (Conrad, loc. sup. cit. p. 48, pi. 8, fig. 3. Hald. pi. 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. Northwest 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 revolvi s on the middle of the body- 

 wliorl, 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. Color, 

 dark horn or blackish; aperture rufous beneath the carina, and at base and apex. Length, 0*4. 

 Pennsylvania. 



P.lapidaria? (Cyclostoma z(f. 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. 



