MELANTHO. 



45 



Fig. 89. 



Paludina genicula. 



I suppose Hig- 



Amnicola; the spire is entirely wanting, but traces of the sutures show 

 tlie number of whirls ; and its present appearance forbids the idea of its 

 ever having had an elevated spire. (^Anthony.) 



The fac-simile which I have given of Haldeman's figure, drawn 

 from the original specimen o? Faludina genicula, Conrad (Fig. 89), 

 would lead one to consider that species identical 

 with Viv. decisa. I do not, therefore, hesitate 

 to unite them ; my opinions are founded on an 

 examination of a series of shells from the locality 

 which furnished Mr. Conrad's specimen, which 

 show a gradual series from the rounded whirls 

 of the decisa to the angular form of genicula, 

 though none of the shells were as well marked 

 as that figured. From other localities, also, I 

 have received specimens of decisa whose six 

 whirls were quite as angular and scalariform. 

 gins refers to some such in quoting Pal. genicula from the Ohio 

 and Scioto Canal (Cat. 6). In Kiister's Paludina (Chemn. ed. 

 2), Cedar Creek As also given as a locality for genicula. Mr. 

 Conrad's description is as follows. Fig. 90 is a fac-simile of 

 his. It is considered identical with decisa by Reeve. 



Paludina genicula.— Shell suboval, spire slightly ele- 

 ^^>x vated ; volutions 4, scalariform, shoulders angulated ; 



L/V^ apex eroded, aperture rather more than half the length 



of the shell ; epidermis green olive ; within bluish. 



A species which is readily distinguished from those 

 nearest allied to it by the angulated whirls. I found 

 a single specimen in Flint River, Ga. (Conrad.) 



, Lymnula ventricosa, Rafinesque, of whose 



Paludina genicula. (jescriptiou and figure (fig. 91) a copy is here 

 given, is evidently this species. 

 His figure, though very rough, is 

 quite characteristic. 



Lymnula ventricosa.— Whirls 4, last 

 one very large ; form obtuse-oval ; 

 aperture bluntly oval, &c. {Uajjues- 

 que.) 



Fig. 91. 



Fig. 92. 



From the same MS., " Con- 

 chilogia Ohioensis," which was 

 presented to the Smithsonian Inst, by Prof. 



Lymnea ehurnea,. 

 Raf. 



