88 new-york fauna — mollusca. 



Amnicola porata. 



PLATE XXXV. FIG. 333. 



Paludina porata. Say, Journ. Acad. Nat. Sciences, Vol. 2, p. 174. 



Amnicola id. Goold, Invertebrata of Mass. p. 229, fig. 157. 



A. id. Haldeman, Jour. Acad. Nat. Sciences, Vol. 8, p. 200. 



Description. Shell very small, obtusely conic or subglobular, thin, smooth or with minute 

 incremental lines. Whorls four, very convex, and flattened near the suture so as almost to 

 present a shoulder : suture very deeply impressed ; spire obtuse ; aperture circular, the lip 

 and pillar-lip being equally rounded, meeting above at a broad angle, the upper edge of the 

 latter appressed to the preceding whorl ; in the adult, barely touching the whorl just before 

 it joins the outer lip, leaving a large and deep umbilicus. 



Color. Olive-green, usually with a soiled coating of mud. Animal flesh-colored ; tentacles 

 silvery ; eyes at the external base with a dark line extending along the tentacles. Length, ' 2. 



First observed at Cayuga lake, but common almost every where in brooks and muddy 

 streams, attached to submerged stones and plants. Allied to A. limosa, but is larger, less 

 solid, more globose, and with a distinct umbilicus. Mr. Haldeman, in the work cited above, 

 describes the shell as " very long and slender, with six obliquely revolving very convex turns, 

 separated by a deep suture : aperture small, ovate, with the peritreme level and continuous, 

 as in Cyclostoma." I cannot venture to reconcile these two descriptions. 



(EXTRA-LIMITAL .) 



A. limosa. (Say, Journ. Ac. Sc. Vol. 1, p. 125.) Shell conic, subumbilicate, obsoletely wrinkled- 

 aperture ovate-orbicular ; suture impressed. Color, dark horn, generally encrusted with a blackish 

 eoat. Animal whitish ; head brown; mouth, tentacles, orbits and vitta on each side of the neck 

 white ; tentacles long and filiform : foot white, brownish above, short, suboval, truncated before, 

 rounded behind. Length, 0*1. Delaware. 



A. grana. (Say, 1. c. Vol. 2, p. 378.) Shell conic-ovate. Whorls convex, not perceptibly wrinkled; 

 suture deeply impressed ; aperture orbicular, hardly angulated above ; pillar-lip with the outer edge 

 appressed to the surface of the penultimate whorl ; umbilicus rather small, profound. Allied to 

 luslrica, but smaller. Length, • 08. Pennsylvania. 



A. cincinnalensis. (Anthony, Bost. Jour. Vol. 3, p. 279, pi. 3, fig. 1.) Shell somewhat ventri- 

 cose, subumbilicate. Whorls four, smooth ; spire prominent and entire at the apex ; suture deeply 

 impressed ; aperture much dilated, approaching to orbicular, nearly half the length of the shell 

 Color, green. Length, 0-2. Cincinnati. 



A nichliniana, Lea. 



