CONCHOLOGY. 



It is doubtftil whether or not this is the 

 same as the Vivipara, but it certainly ap- 

 proaches very near to it ; we however re- 

 fur it to that species until a specific dif- 

 ference can be indicated, which at pre- 

 sent -we are unable to do; the spire of 

 this species is rather more obtuse, and 

 the suture not so deeply impressed, as in 

 the figures of the European specimens 

 above mentioned. 



6. /. Decisa. Shell subconic, oliva- 

 ceous, truncated at the apex; whorls 

 four, wrinkled across and banded with 

 minute distant strix ; 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 virginiana e fav a viridetcens, 

 nonfasciata. 



Litter, 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. 



GKM-S OUOSTOMIA. 



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. 0. Corticaria. Shell dextral, cylin- 

 drical, obtuse at the apex ; whorls five, not 

 perceptibly wrinkled or striate. 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 J\fus- 

 corum of Authors 



BIVALVES. 



GKHUB I'M". 



Shell transverse^, with three deeply 

 impressed cicatrices ; hinge with a strong 

 irregular tooth and anterior laminated 

 one in one valve, inserted between two 

 corresponding teeth and laminx of the 

 other. 



Obs. The shells of this genus gene- 

 rally inhabit fresh water : they were 

 placed by Linnaeus with the my*, from 

 which they differ in very essential par- 

 ticulars ; as is obvious from the number, 

 situation, and figure of the teeth, and 

 the organization and habits of the inclu- 

 ded animal. 



U. Crasnts. Shell varying in form 

 and surface ; remarkably thick and pon- 

 derous; epidermis horn-colour, differ- 

 ent shades of brown or black ; beaks ca- 

 rious, often much eroded, pure pearlace- 

 ous, or silvery white, more prominent as 

 the shell approaches an orbicular form ; 

 primary teeth, not very oblique. The di- 

 mensions of three specimens were as fol- 

 low : 



Length, 3 inches ; breadth, 4 

 2 4$ 



2 2 



Plate 1. fig. 8. 



JtfutcuKs brevoir, admodum crassvt, ex 

 interna parts tubroseus, cardine incisuris 

 iiinutis exasperato. 



Litter, conch, tab. \SQ.fig. 5. 



By these dimensions it will appear to 

 vary very considerably, being a regular 

 oval ; much elongated, ovate, or nearly 

 orbicular ; sometimes with two or three 

 longitudinal or oblique waves ; rarely tu- 

 be re u 1 ate ; within pearlaceous or red pur- 

 ple ; teeth very thick, crenated, and re- 

 sembling those of the next species. It is 

 very probable that we have here includ- 

 ed several distinct species, but at pre- 

 sent we are not sufficiently well acquaint- 

 ed with the inhabitants to separate them. 

 Gmelin refers to Lister's figure for his 

 Mytillus Cygneus, but we can discover 

 no resemblance between them. 



Found plentifully in the river Ohio and 

 its tributary streams. 



An undulated variety was found by 

 Mr. C. A. Letuevr in Lake Erie ; its cha- 

 racters agree for the most part with 

 those given above, but the undulations do 

 not terminate at one end in the beak, but 



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