38 



VIVIPARA. 



Fig. 68. 



Vivipara troosti- 

 ana. 



nob., and especially P. intertexta, nob., of which latter, in fact, I at first 

 supposed it to be the young, in consequence of its rotundity and the simi- 

 larity of its capillary lines ; but inasmuch as the number of its whirls is 

 nearly the same, whilst the magnitude differs so greatly, I have separated 

 it as a different species. 



Vivipara troostiaiia, Lea — Shell ventricose-conical, thin, pellu- 

 cid, yellowish horn color, smooth, perforate ; spire short ; sutures very 

 much impressed ; whirls four, convex ; aperture large, rounded, white. 



Tennessee. Prof. Troost. My cabinet, and cabinet of Prof. Troost. 

 Uiam. .68, length .72 inch. 



This is a subglobose species, differing from any which 

 has come under my notice, in having the superior por- 

 tion of the last whorl somewhat flattened, giving the 

 shell a somewhat gibbous appearance. The operculum 

 is rather of a light color, and the plane of the aperture 

 is very retuse at its base. It has a strong resemblance 

 to P. unicolor (Lamarck), and perhaps a stronger one 

 to P. Maheyana (Grateloup). It is more depressed in 

 the spire than either, and the perforation is smaller than 

 in the former, while it is nearly the size of that in the 

 latter. The aperture is larger than either. Dr. Grateloup has very pro- 

 perly, I think, separated the Malabar species from that which was observed 

 by Olivier in Egypt, and called unicolor by Lamarck. The Egyptian shell 

 has a larger perforation, is darker in color, and is a larger species. I call 

 this after my friend Prof. Troost. (Lea.) 



Paludina troostiana, Lea, Tr. Am. Phil. Soc. IX, p. 14 (1844). Obs. IV, 



p. 14. Proc. II, 34 (1841). Arch. f. Nat. 1843, II, 130. 

 Paludina haleiana, Lea, 1. c. p. 96, pi. ix, f. 58 (1847). Obs. IV, 70. 

 Proc. IV, 167 (1845). 



I have added to Mr. Lea's description of V. troostiana a view 

 of the type (Fig. 68) in his collection. It will not seem to cor- 

 respond very exactly with the figure of haleiana, of which a fac- 

 simile in outline is given below (fig. 69). A comparison of all 

 of Mr. Lea's specimens of each has convinced me, however, of 

 their identity. Mr. Lea's description of the latter species here 

 follows. 



Vivipara haleiana, Lea — Shell smooth, ventricosely conical, 

 rather thin, reddish horn-color, imperforate ; spire short ; su- 

 tures much impressed ; whirls four, nearly convex ; aperture 

 large, nearly round, bluish. 



Diameter .4, length .55 inch. Alexandria, La. 



Til's species is nearly allied to the Pal. troostiana, nob., 

 but is rather smaller, of a darker color, not quite so rotund, 

 and imperforate. These differences would distinguish it 



Fig. 69. 



