VERTIGO. 



443 



Fig. 704. 



comb ; one on the middle of the transverse lip, a still larger one at 

 right angles on the middle of the pil- 

 lar lip, a minute one at the front of 

 the pillar, and two farther within the 

 shell, one opposite the tooth on the 

 transverse lip, the other on the in- 

 dentation of the outer lip ; umbilicus 

 small, distinct. Length, three for- 

 tieths of an inch ; breadth, one twen- 

 ty-fifth of an inch. 



Inhabits damp, rich places near 

 water, or in fertile fields under bits 



of board, chips, sticks, &c. It was first noticed in this region by 

 Mr. T. J. Wliittemore, at Caml)ridge. From Maine to Texas. Also 

 quoted from Mexico and Cul)a. 



It is a very small, but interesting shell ; d()ul)lo the size, how- 

 ever, of V. mil ill 1)1^ and of a much more conical shape. Their color 

 is similar. In their armature the two are very different. The pil- 

 lar lip is somcwliat broad and flattened. 



Mr. Say describes only four teeth, but the small one at the base 

 of the pillar ])ro!)ably escaped his observation, as it would only be 

 seen under a high magnifier. One of the teeth on the right lip is 

 often wanting. I have occasionally noticed a specimen with two, 

 and even three, teeth upon the transverse lip. 



Vertigo ventricosa. 



Shell ovate-conic, smooth; whorls four; aperture semi-circular, with five 

 teeth ; umbilicated. 



Isthmia ventricosa, Morse, Ann. N. Y. Lvc. viii. 1, fiijs. 1 -.3 (Nov. 1865). 

 Vertigo ventricosa, Morse, Am. Nat. i. 669, figs. 61, 62 (1868). 



Shell umlMlicate, ovate-conic, smooth, pol- 

 ished ; apex obtuse ; suture deep ; whorls 

 four, convex ; aperture semi-circular, with 

 five teeth, one prominent on the ])arietal 

 mai'gin, two smaller on the columcllar mar- 

 gin, and two prominent within, contract- 

 ing the aperture at the base ; jieristome 

 widely reflected, the right margin flexu- 

 ose, within thickened and colored. Length, seven hundredths of 

 an inch ; breadth, forty-five hundredths of an inch. (^Morse). 



V. ventricosa. 



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