162 



NATURAL HISTORY OF VERMONT. 



Part I. 



FKESH WATER AND LAND SHELLS. 



of the penult whorl ; labrum sharp; um- 

 bilicus concave, very broad and deep, ex- 

 hibiting very distinctly all the volutions 

 to the apex ; far within the aperture may 

 often be seen a pair of conical teeth on the 

 inner side of the outer whorl, one on the 

 middle, the other below ; sometimes one 

 is obsolete ; often a second and sometimes 

 a third pair may be seen through the sides 

 of tlie shell much farther within. Great- 

 est breadth 0.14 inch ; least breadth 0.13 

 inch ; height O.OG inch ; divergence never 

 less than IGU'-', usually 170^. *■ 



Remarks. — Above, this shell resembles 

 H. muUiihntat.a, in the depression of the 

 epire and narrowness of the whorls, but 

 in the other characters is very different. 

 No other native species has such revolv- 

 ing minute carinaF!. It has been found 

 in the northern and middle states. 



Helix striatclla. — Anth. 



Description. —Shell depressed-convex, 

 with very much crowded deep incremen- 

 tal strifE ; epidermis reddish or yellowish 

 brown ; whorls four, convex, with a well 

 impressed suture, moderately increasing 

 in diameter ; aperture nearly circular, 

 Blio-htly modified by the intrusion of the 

 penult whorl ; labrum sharp ;. umbilicus 

 not so wide as the last whorl, deep, dis- 

 tinctly exhibiting the volutions to the 

 apex. Greatest breadth 0.25 inch ; least 

 breadth 0.22 inch ; height. 0.12 inch ; di- 

 vergence 140'' to l.oO". 



Remarks. — This species is quite com- 

 mon in Vermont. It resembles H. per- 

 spectiva, Sav, a species, which has not 

 been found in the New England states. 

 The latter has one or two more whorls, 

 the umbilicus much wider, and the strife 

 much coarser It is also a larger shell. 

 This species does not appear to differ 

 from the European shell, H. ruderata^ 

 Studer. Comparing specimens from 

 Stiria with those of Vermont, we are un- 

 able to detect any difierence. But as 

 Bome naturalists are not convinced of their 

 identity, we have retained the name of 

 the American author, although the Euro- 

 pean name has the priority of many years. 



Helix alternate/.. — Say. 

 DEScRiPTioN.-Shell depressed-convex, 

 with acute, raised, equi-distant obliquely 

 curved stria3, whicii render the sliell sca- 

 brous ; epidermis horn color, variegated 

 with rufous spots and bars obliquely ar- 

 ranged ; whorls six, convex, with a well 



impressed suture ; aperture very oblique, 

 nearly circular, brilliant, sometimes pearly 

 within; labrum sharp: umbilicus broad 

 and deep, exhibiling all the volutions ; 

 beneath, the colored bars are more regu- 

 lar, and converge into the umbilicus : they 

 are interrupted by a colorless zone a little 

 below the middle of the last whorls. Great- 

 est breadth 1 inch ; least breadth 0.87 

 inch ; height 0.59 inch ; divergence 125° 

 to 135°. 



Remarks. — This species has been found 

 throughout most of the territory of the 

 United States. It is very common in this 

 state, living under stones and logs on 

 hill-sides in rather moist but not wet pla- 

 ces. When young, its outline is carina- 

 ted. It resembles the H. radinta, of Eu- 

 rope, but cannot be mistaken for any oth- 

 er American species. 



Helix chersina. — Say. 



Description. — Shell elevated and con- 

 ic above, convex and shining beneath, 

 striff! of growth excessively minute ; epi- 

 dermis brownish amber-colored ; whorls 

 six, very convex, with a deep suture, not 

 increasing much, so that the last is but 

 little larger than the penultimate whorl ; 

 aperture very wide, reaching to the axis 

 beneath, much modified by the intru- 

 sion of the penultimate whorl ; labrum 

 sharp; umbilical region indented. Great- 

 est breadth O.llS iach ; least breadth 

 0.105 inch; height 0.09 inch> divergence 

 90° 



Remarks. — This and H. lahyrinthica 

 are distinguished from other native spe- 

 cies of Helix by the elevation of the spire, 

 and are very distinct from each otiier in 

 most characters other than size and form. 

 The species is not very rare in this state, 

 and having been found in Georgia and the 

 North West Territory, is, no doubt, wide- 

 ly dispersed. From its minute size it is 

 liable to escape detection. 



FAMILY LIMACIANA. 



Genus Vitrina. 



Generic Charedcrs. — Shell wiih a depressed, 

 convex, obtuse spire, with but few whorls, of 

 which the last is extremely large ; the aperture is 

 very large, wider than long, interrupted hy the pe- 

 nult whorl ; umbilicus wanting. The shell is e.K- 

 tremely ihin and transparent, and is capable of 

 containing only a part of the animal. No op- 

 erculum. The auimnl is much loo large lo enter 

 the .shell, resembling a Helix. Ii is long, mostly 

 straight, with the posterior part distinct, spiral, 

 protected by the shell; with four tcmaclcs, of 

 which the anterior pair is very short. 



Vitrina pellucida. — Drap. 

 Description. — Shell globose-discoid, 

 shinino-, with the incremental striaj ex- 



