VIVIPARA. 



27 



Fig. 42. 



Fig. 41. 



Fie. 43. 



in the Southern as well as Northern States. Prof. Haldeman's 

 original specimen of Pal. rufa, together with all those from which 

 the plates of his Monograph were drawn, are deposited by him 

 in the collection of the Academy at Philadelphia. Pig. 40 is a 

 fac-simile of the figure referred to by Haldeman under this name. 

 No. 8905 of the collection represents it. 



Figure 41 is a fac-simile of 

 Helix dissimilis, Wood, of 

 which no description nor local- 

 ity is given. It is evidently in- 

 tended for this species, though 

 the true name decisa is applied 

 by Wood to a figure of sub- 

 carinata. I also give a fac- 

 simile (fig. 42) of Lister's figure. 



No. 8921-4 of the collection were presented 

 by Dr. James Lewis under the unpublished name 

 of Paludina obesa, Lewis. Fig. 43 represents 

 one of them. This form is a well marked variety, 

 found near Mohawk, N. Y., in Ohio, and Mich- 

 igan. It is readily distinguished by its very 

 ventricose, rounded form and dark olive green 

 color. Some small specimens resemble forms of 

 F. regularis, Lea. Its name is preoccupied. 

 The fac-simile which I have given of Halde- 

 man's figure, drawn from the original specimen 

 of Paludina genicula, Conrad (fig. 44), would 

 not lead one to consider that species identical 

 with Viv. decisa. I do not, however, 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 spe- 

 cimens of decisa whose six whirls were quite as angular and 

 scalariform. I suppose Higgins refers to some such in quoting 

 Pal. genicula from the Ohio and Scioto Canal. In Kiister's 

 Paludina (Chemn. ed. 2), Cedar Creek is also given as a locality 



Paludina obesa. 



Fig. 44. 



Paludina genicula. 



