CONCHOLOGY. 



retaining a proper specific gravity. The 

 apex is often truncated. 



This species was found by Mr. Thomas 

 Nuttall, during a journey to Pittsburg. 



7. L. Decisa. Shell subconic, oliva- 

 ceous, truncated at the apex; whorls 

 four, wrinkled across and banded with 

 mtnute distant strise ; terminal whorl very 

 short ; suture impressed and conspi- 

 cuous; aperture subovate, more than half 

 of the length of the shell, entire ; within 

 bluish white. Operculum coriaceous, 

 elevated on the disk and concentrically 

 striated. 



Length one inch ; breadth three-fourths 

 of an inch. 



Plate 2. fig. 6. 



Cochlea virgiiuana e fava viridescens, 

 nan fasciata. Lister, conch, tab. 127". fig- 

 27. 



The young shells resemble L. subcari- 

 nata, but the whorls are destitute of an 

 elevated line, the suture is not so deeply 

 impressed, and the aperture is narrower 

 above. 



Animal with the foot large, suddenly a 

 little dilated each side before and truncate 

 in front, widely ; foot livid, thickly macu- 

 lated with irregular orange spots, which 

 are much smaller beneath ; head and ten- 

 tacula spotted with orange; eyes on a pro- 

 minent angle, at the external base of the 

 tentacula. 



I found the animal viviparous iu Octo- 

 ber ; the young shell had then three 

 complete whorls, which were spirally stri- 

 ated. 



GENUS PCPA. 



Shell spiral produced. Aperture con- 

 tracted, subangular, generally distinct, 

 and sometimes separate from the body 

 whorl, and usually furnished with teeth. 



Observ. The shells belonging to this 

 genus have been divided with much pro- 

 priety from the Linnxan Genus Turbo ; 

 they inhabit moist places, under the bark 

 of trees, under stones, moss, &c. many of 

 them are sinistral. 



1. P. Corticaria. Shell dextral, cylindri- 

 cal, obtuse at the apex ; whorls five, not 

 perceptibly wrinkled orstriate. Aper- 

 ture suborbicular, lip reflected ; a single 

 tooth on the pillar lip near the outer an- 

 gle ; inner angle with an angular projec- 

 tion resembling a second tooth, some- 

 times obsolete. 



Length about the tenth of an inch. 



Plate 4. fig. 5 A. Natural size ; C. An 

 enlarged view. 



Very common under the bark of trees 

 near the earth, and resembles Turbo Mus- 

 corum of authors. 



GENUS POLYPHEMUS, Moiltf. (ACATHNIA, 

 I.AMARCK.) 



Shell oblong ; aperture much longer 

 than broad, perpendicular and parallel to 

 the column ; lip not reflected ; columella 

 gradually incurved towards the tip ; tip 

 truncated. 



P. glans. This shell furnished De 

 Montfort with the type of his genus po- 

 lyphemus ; he refers to Briiguiere as the 

 first describer of it, under the name of 

 Bulimus glans, in the Encycl. Method. 

 The animal has not been described, but 

 we are informed that it lives in the im- 

 mense marshes formed by the overflow 

 of the great rivers that water the vast 

 country of Louisiana. In the sea-islands 

 of Georgia we fpund them numerous in 

 the marshy districts, immediately behind 

 the sand-hills of the coast; in Florida in 

 similar situations, and also on the Oyster- 

 shell Hammocks, and generally in such 

 situations as are tenanted by Succinea 

 compestns. The colour of the shell on the 

 spire is chesnut-brown, which gradually 

 and very perceptibly becomes paler to 

 the aperture, aperture occupying about 

 half the length of the shell. On elevated 

 situations they were small, almost trans- 

 parent, and of a fragile consistence. It is 

 only in low, marshy situations, that they 

 attain their greatest size. 



Length two inches and two-fifths 

 breadth one inch nearly. 



Animal elongated, as long again as the 

 shell, granulated ; tentacula four, supe- 

 rior ones oculiferous, abruptly deflected 

 at tip, beyond the eyes; inferior ones 

 much shorter, and abruptly deflected 

 at tip ; lips beneath the tentacula, elon- 

 gated, palpiform, almost as long as the 

 superior tentacula, retractile, generally 

 more or less recurved, compressed, at- 

 tenuated, and acute at tip, and forming 

 a considerable interval between their pro- 

 minent bases. 



When the animal is in motion, the 

 elongated lips are used as tentacula to 

 feel the way. 



BIVALVES. 



GENUS UNIO. 



Shell transverse; with three deeply 

 impressed cicatrices ; hinge with a strong 



