43 



LAND AXD FRESn- WATER SHELLS OF N. A. [PART HI. 



dina Integra. I have, therefore, copied below Ids description, 

 and given a figure (96) of liis typical specimen still preserved in 

 the collection of the Philadelphia Academy. 



Paludina integrn, Say. — Shell olivaceous, pale, conic ; whirls six, wrin- 

 kled across ; spire rather elongated, entire at the apex; suture profoundly 

 indented ; ajjerture subovate, less than half of the 

 Fig- 96. length of the shell. 



Inhabits the waters of the Missouri. Length | 

 inch. 



Very much resembles P. decisa ; the spire, how- 

 ever, is more elongated, and never truncated at 

 the apex, but always acute. {Say.) 



Paludina intfgrn. 



The dimensions given above are probably 

 a tj'pographical error. 



The large number of specimens which I 

 have had the opportunity of examining have 

 exhibited so many and so slight degrees of 

 difference between M. decisa and 31. integra, 

 that I am persuaded of their specific identity. I am supported 

 in this view l)y the recent monograph of Mr. Reeve, but opposed 

 in it by most of the American collectors. I have given below a 

 description and figure of what is usually acknowledged to be 

 Paludina integra. The difference of form of the sexes is shown 

 also, Fig. 98 being male. Fig. 97 being female. 



Mdantho decisa, var. integra. — Shell imperforate, elongate-ovate, quite 

 thick, smooth, surface hardly broken by lines or wrinkles of growth, 



marked with delicate re- 

 Fig- 97. Fig. 98. volving strise ; greenish, 



with darker streaks, mark- 

 ing the edge of former peri- 

 stomes, uniformly chalky 

 white under the epidermis ; 

 spire elongated-conic, apex 

 perfect, acute ; whirls 5, con- 

 vex, the last equalling two- 

 thirds the shell's length, 

 imperforate ; aperture oval, 

 narrowed above, oblique, 

 more than half the length 

 of the body whirl, milky 

 white within ; jieristome ex- 

 ternally of a darker color, simple, acute, somewhat sinuous, its terminations 

 joined by a thin, transparent callus on the parietal wall of the aperture, 



Vemalo of M. (Ucisa, 

 var. inlp.gra. 



Male of M. decisa, 

 var. intfgra. 



