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, 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 *5. 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. (Sav, Am Conch, pi. 10.) Shell subconic. Whorls 4, rounded; aperture suborbicu- 

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

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

 South- Carolina. 



P. magnifica. (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 striae. 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 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*8. 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 eonic. 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. Color, 

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

 Pennsylvania. 



P.lapidaria? (Cyclostoma 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. 



