VIVIPARA. 



19 



Fig. 28. 



Fig. 29. 



Inhabits with the preceding species. (Delaware River.) 

 Animal viviparous, with a chestnut, coriaceous operculum, white, spotted 

 with orange ; head pale orange, not extending beyond the shell ; tentacula 

 darker, short, subulate ; eyes situated at their base, elevated, black and 

 conspicuous ; base of the animal much advanced, broad, truncate, purplish 

 before, tail rounded behind. 



Paludina subcarinata, Sat, 1816, Nich. Enc. pi. i, f. 7 (^Limncea of earlier 

 ed.) ; ed. Binney, p. 47, pi. ixix, f. 7. — Haldeman, Mon., p. 8, pi. ii 

 (1840).— De Kay, N. Y. Moll., p. 86 (1843).— Chenp, Conch. 111., pi. 

 i, f. 6-8. — Philippi, Conch. II, 135, pi. li. f. 7. — Kustee, in Chemn., 

 ed. 2, p. 29, pi. vi, fig. 10-14. — Not of Potiez et Michaud. 

 Paludina sulculosa, Menke, Syn. Meth. p. 134. 

 Paludina bicarinata, Potiez et Michaud, Gal. des Moll., I. 249, pi. xxv, f. 



17, 18. 

 Helix decisa, Wood, Cat. Suppl. vii, f. 17 (1828). 



There are in the mature perfect shell 

 3 more whirls than the number given 

 by Mr. Say. It is a very variable shell. 

 The whirls are sometimes truncated at 

 the apex, very much rounded and hard- 

 ly marked by the carin?e (fig. 28), which 

 in other localities are much developed, 

 continuing to the sharp, well defined 

 apicial whirls, on which is no trace of erosion (fig. 29). 

 Sometimes there is a prominent revolving elevated ridge below 

 the carina on the body whirl. The revolving strife are sometimes 

 very strongly marked. 



The lingual organ is figured by Troschel (Gebiss der Schneck- 

 en, p. 100, pi. vii, f. 5). 



The great peculiarity of the species is its opercu- 

 lum, which in the young shell is subspiral, while the, 

 later growth is concentric as in the other species. 



I have received specimens from Ohio, Indiana, 

 Kentucky, Pennsylvania, and New Jersey. 



Paludina sulculosa, Menke, 1. c, appears to me to 

 be this species. I have seen no authentic specimen 

 scription is as follows : — 



Paludina sulculosa. — Shell ovate-conoid, apex deroded ; imperforate, thin, 

 decussately striated, transversely lightly sulcated ; green ; whorls 4, angu- 

 lated on the spire; suture deep ; aperture ovate ; lip simple. Length 4j, 

 breadth 3 lines. 



Ohio River at Cincinnati. Bescke. {Menke.} 



Fig. 30. 



Operculum of 



Vivipara 

 subcarinato.. 



His de- 



