152 



NATURAL HISTORY OF VERMONT. 



Part I. 



FRESH WATER AND LAND SHELLS. 



was found in Otter Creek, inMiddlebury. 

 Paludina Integra. — Say. 



Description. — This species so much 

 resembles the preceding, that a formal de- 

 scription is unnecessary. Its apex is not 

 truncated, so that, with a greater diver- 

 gence of the spire, it is, nevertheless, 

 longer than that .shell. It is also thicker, 

 and the whorls are less convex. This 

 shell is common in the western states, but 

 it is extremely rare in Vermont, only three 

 or four specimens having been obtained 

 in lake Ciiamplain. Length 1.3 inch; 

 breath 0.75 inch ; divergence of the spire, 

 63-'. 



Paludina porata. — Say. 



Description. — Shell conic, horn col- 

 or ; whorls four and a half, convex ; su- 

 ture rather deep; apex subacute, spire as 

 Ion<T as the aperture, the labium of which 

 is appressed to the penultimate wliorl ; 

 umbilicus rather large. Length 0.27 in. ; | 

 breadth 0.1!) inch ; divergence of the 

 spire 72°. 



Remarks. — This species is found plen- 

 tifully in streams and in lake Champlain. 

 It is sometimes brownish or greenish. 



Paludina lustrica. — Say. 



Description. — Shell ovate-elongate, 

 horn color ; whorls four and a half, con- 

 vex ; suture rather deep ; apex very ob- 

 tuse ; spire as long as the aperture, whicli 

 is ovate-orbicular, with the labium not 

 appressed to the penultimate whorl, and 

 sometimes scarcely touching it ; umbili- 

 cus small. Length 0.16 inch; breadtli 

 0.11 incii ; divergence of the spire 47". 



IvEMAiiKS. — Tliis small species is com- 

 mon in lake Champlain. It differs from 

 the preceding in the obtuseness of the 

 apex, less divergence of the spire, and 

 small umbilicus ; also in the labium, 

 which is quite distinct from the penulti- 

 mate whorl, so that the shell much I'esem- 



blcs a valvata. 



Genus Valvata. 



Generic Characters. — Shell discoid or co- 

 Boid ; whorls cylimirical ; apLriure orbicular, not 

 modified by die penult iiiiale whorl ; margins con- 

 linuoiis,dislincl fiomlhe peiiultiniatc whorl. Oper-- 

 culuin orbicular, concentric. Animal with I lie 

 foot bilobed before ; head proboscidilonn ; tenta- 

 cles very lona, slender, oblu&e, cylindrical ; eyes 

 sessile behind the leaiacles, with a branchial fil- 

 ament resembling a third tentacle. 



Valvata tricarinata. — Say. 

 Description. — Shell depressed, conic, 

 thin, green, obsololely striate , suture 



well impressed ; whorls three or four^ 

 rendered subquadrangular by the revolv- 

 ing carime, of which two appear on 

 the spire, and three on the last whorl ; 

 these are very much raised, rounded^ 

 equi-distant, the inferior bordering the 

 umbilicus, which is broad and deep. — 

 Length 0.13 inch; breadtli 0.22 inch ; di- 

 vergence of the spire U0°, sometimes 

 much greater. 



Reji ARKS. —This shell, very curious on 

 account of its carinas, is common in lake 

 Champlain, and in some of our streams. 

 Varieties occur in which the middle cari- 

 na is obsolete, or in which none are very 

 distinct.* Other varieties have the spire 

 less elevated, or even in the plane of the 

 last whorl. 



Valvata sincera. — Say. 



Description. — Shell globose-discoid, 

 obsolctely striate,brownish-green ; whorls 

 three and a half, accurately rounded, rap- 

 idly enlarging to the aperture ; suture 

 deeply impressed ; spire but little eleva- 

 ted ; apex obtuse ; umbilicus deep, about 

 two-thirds as wide as the last whorl ; mar- 

 gin of the aperture touching the penulti- 

 mate whorl. Length 0.1 ; breadth 0.2 

 inch ; divergence of the spire about 135° 



Remarks. — This shell is much like the 

 va.r. simplex of the preceding species. 

 The umbilicus is usually a little larger, 

 but the most striking characteristic is the 

 rapid enlargement of the whorls, the last 

 being more than three times the diameter 

 of the penultimate. The divergence of the 

 spire is never so .small as in that species, 

 but like that is sometimes much more 

 than in the type of the species, even to 

 180°. 



FAMILY MELANIANA. 

 Genus Melania. 

 Generic C/Mraders.— Shell turrited ; aperture 

 entire, ovate, etfuse ; columella thickened, arcuate. 

 Operculum horny, sub'^piral. Animal oviparous ; 

 foot short ; rostrum truncate ; tentacles filiform-, 

 with the eyes outside, at or near iheir base. 



Melania dcpygis. — Say. Var. 

 Description. — Shell elongate-conic, 

 yellowish linrn-color, with abroad rufous 

 band on the whorls of the spire, with a 

 second similar band on the lower third of 

 the last whorl ; upper whorls carinate on 

 the lower side ; whorls eight or nine ; 

 spire twice as long as the aperture. Length 

 0.53 inch ; breadth 0.22 inch ; divergence 

 of the spire 33°. _^ 



» Var. simplex. -Goolb 



