356 THE CHICAGO ACADEMY OF SCIENCES. 



GENUS CAMPELOMA Rafinesque, 1819. 

 Paludina, Vivipara and Melantho of authors. 



"Shell: Thick, solid, ovate, imperforate, spire produced; 

 whorls rounded, smooth, covered with an olivaceous epider- 

 mis; peristome simple, continuous." (W. G. Binney.)* 



Animal: With a large, broad, rather thin foot, "much 

 produced beyond the snout and slightly auricled in front. 

 Color rather light, in reddish (orange) spots on a palish white 

 ground. Head of moderate size, snout small. Lingual teeth 

 smooth or only minutely crenulated at their apices. Cervical 

 lappets of moderate size, but not forming regular tubular 

 aquiferous ducts; the right one plicated. Branchial laminae 

 elongate-triangular, equal in size and arranged in a single 

 straight row both at base and tips." (Stimpson.)f 



"The operculum is elongately-ovate, somewhat produced 

 anteriorly and curved; thin, corneous, subconcentric, with sim- 

 ple nucleus near parietal wall; reddish or light brown." (Call.) 



Disribution: The United States east of the Rocky Moun- 

 tains. 



KEY TO SPECIES OF CAMPELOMA. 



A. Shell reddish or pinkish under the epidermis, especially the 



apex rufum 



B. Shell dark olivaceous or greenish, chalky-white beneath the 



epidermis. 



a. Spire very short, stumpy; aperture longer than spire, 



produced into a sort of channel at the upper (poste- 

 rior) part; shell very ponderous ponderosum 



b. Spire rather long, aperture and spire of equal length, 



aperture not produced. 



1. Whorls rounded; shell generally ovate, rather thin, 



spire somewhat depressed, aperture rounded decisum 



2. Whorls rather flattened; shell generally elongated, 



solid; spire produced, aperture sigmoid subsolidum 



147. Campeloma ponderosum Say, pi. xxxv, fig. 9. 



Paludina ponderosa SAY, Journ. Phil. Acad., Vol. II, p. 173, 1821. 

 Paludina regularis LEA, Trans. Amer. Phil. Soc., Vol. IX, p. 13, 1844. 

 Melantho nolani TRYON, Con. Haldeman, Mon., p. 25, pi. xii, figs. 

 10-11, 1870. 



Shell: Very heavy and solid, globosely ovate; color gen- 

 erally greenish, but blackish in old specimens and showing 

 old peristome scars; surface shining, polished, smooth, lines of 



*L. and Fr. W. Sh., pt. 3, p. 36. 



tSee Bull. Washburn Coll. Lab. N. H., Vol. I, No. 5. p. 153. 



