20 



LAND AND FRESH-WATER SHELLS OF N. A. PART III. 



Fig. 33. 



Fig. 34. 



The labnim exhibits no curvature from the middle almost to its junctioa 

 with the penultimate volution. ^ 



Shell subglobular oval, not remarkably thickened; spire longer than the 

 aperture, entire at the tip ; whirls five, slightly wrinkled across, rounded 

 but not very convex ; penultimate volution somewhat elongated ; suture 

 impressed ; aperture ovate-orbicular, less than balf the length of the shell ; 

 labium with calcareous deposit ; animal very pale bluish, with minute 

 yellow points, particularly on the rostrum, tentacula, and prominent re- 

 spiratory tube, which is as long as the tentacula ; eyes on the exterior 

 side of the tentacula, near the middle of their length ; the 

 anterior portion of the foot is very short. 



This species was first found by Mr. Lesueur and Dr. 

 Troost, in Fox. River of the Wabash. In the young state 

 the figure is subglobose, and the aperture, although it 

 hardly diifers in form from that of the adult, is yet longer 

 than the spire. They become proportionally more elon- 

 gated as they advance in age, and the form, therefore, of 

 the adult, is so difl'erent from that of the young or half 

 grown, that in these states it may, very readily, be mis- 

 taken for a widely distinct species. 

 The color of the shell is variable. In some it is pale horn, more tinged 

 with yellowish than with green ; in others are traces of obso- 

 lete purplish bands ; in many specimens the whole shell is 

 reddish-purple, more or less obscure in different individuals. 



In the autumn it is frequently found between the valves of 

 dead Unios, in which it enters perhaps to hybernate. The 

 species is certainly allied to the vivipara, but it cannot well 

 be mistaken for it, as it is mucb less dilated, the volutions 

 less convex ; the penultimate volution is much longer in pro- 

 portion to the length of the body whirl, and the umbilicus is 

 obsolete. {S'lij.) 



Paludina suhpiirpurrn, Say, 1829 ; N. H. Diss. II, 245 ; Am. Conch. Ill, 



pi. sxx, f. 2, 1831 ; Binney's ed. p. 146, 185, pi. xxx, f. 2 ; ed. 



Chexu, 41, pi. xi, f. 6 — Haldeman, Mon. p. 28, pi. ix, 1841. — DeKay. 



N. Y. Moll. p. 86 (1843).— Kuster, Chemn. ed. 2, p. 12, pi. ii, fig. 



10-13 ; pi. vii, fig. .3-5.— Reeve, Con. Icon. 47, Feb. 1863. 

 Vivipara terana, Tryon, Pr. Ac. Nat. Se. (fig.), Sept. 1862, p. 451.— 



Reeve, Con. Icon. 24 (Feb. 1863). 



Mr. Say's original specimens of this species are still preserved 

 in the collection of the Philadelphia Academy. Fig. 35 is taken 

 from one of them. 



The surface is often quite smooth and shining, the spire more or 

 less elongated and slender, but generally distinguished by the 

 penultimate whirl, \Yhich is very much larger than is usual in our 



