[74] 



chologists, but the weight of opinion has been in favor of con- 

 sidering it identical with Vallonia pulchella of Europe. Mr. 

 E. S. Morse has recently critically compared the two species, 

 and discovered several differences which we have been able to 

 confirm fully. V. minuta is more depressed, the whorls are not 

 as large, the aperture wider, and the labrum not so much 

 rounded above, while below it ends further towards the axis of 

 the shell ; the lip of V. minuta is at an angle of 27° from a 

 line passing through the axis, while that of V. pulchella is 35°. 

 The lingual dentition also differs. In order to exhibit the above 

 differences in the shell satisfactorily, I have copied Morse's 

 figures of V. minuta and V. pulchella, fig. 1 representing the 

 latter. European authors have separated from V. pulchella a 

 species in which the striae of growth are occasionally elevated 

 into ridges, under the name of V. costata. I doubt the validity 

 of this distinction, which is of importance to those American 

 conchologists who maintain the identity of our shell with the 

 European pulchella from the fact that in certain localities we 

 also have the costate variety. Helix alternata and several other 

 species of native Helices exhibit quite as great diversity as the 

 minuta in this respect, and I am inclined to attribute the develop- 

 ment of these ridges in the growth of the shell to local disturb- 

 ing influences.* 



ULOSTOMA, Albers. 

 t Shell handed ; no parietal tooth. 



1. Ulostoma profunda, Say. 



Plate 7, fig. 3. 



Orbicularly depressed ; whorls 5 — 6, convex, strongly obliquely 

 striate, with well-impressed suture ; aperture subcircular, lip 

 large, white, its extremities approaching with an obtuse tooth on 

 the inner basal edge ; base convex, umbilicus large, profound. 

 Light horn color, with generally a broad reddish brown band 

 above the periphery, and numerous narrow bands on the base, 

 sometimes uniform pale horn color. 



Diam. 28 mill., height 15 mill. 



Western New York to Virginia, and eastwards to Nebraska. 



*''The molluscous fauna of Harper's Ferry is distinguished for the de- 

 velopment of heavy lines of growth, and acute prominent cariniE on the 

 shells of the species ; and in the terrestrial shells by the depression of 

 the spire." Tkyon onthe Mollusca of Harper's Ferry, Va., Proceed. Acad. 

 Nat. Sci. Phila., 1861. The same features obtain in the species of the 

 mountainou district of Bast Tennessee. 



