THE NATURAL HISTORY SURVEY. 357 
growth numerous, fine, crowded, crossed by delicate spiral 
lines; beneath the green or black epidermis the shell is pure 
white; apex always eroded in old specimens but in young ones 
showing a small, round, sunken nucleus, which is light horn 
color; spire generally depressed, short, conic; sutures well im- 
pressed; whorls six, rounded, bulbous or inflated, the last 
whorl very large, equaling over half the length of the entire 
shell; aperture elongately-ovate, rounded below and con- 
tracted above, where it is produced into a sort of canal; aper- 
ture bluish-white within; peristome sharp, thick, simple, mar- 
gined with black; columellar lip covered by a thin coating of 
callus, which is bordered with black and which makes the peri- 
stome entire, joining the terminations; base of shell rounded, 
imperforate. 
Length, 21.50; width 15.00; aperture length, 138.50; width, 8.00 mill. (8848.) 
3 S00 ee lS. 50% & Saal tt (0) remeniee emma (OK) mice (8848.) 
Animal: Not examined. Operculum longer than wide, 
much narrowed above, convex, horny, thin on the edges, sub- 
concentric; the nucleus near the left margin; reddish brown 
incolor. Length 12.50, width 7.comill. (Shell 21.50 mill. long.) 
Radula: Not examined. 
Distribution: New York west to Illinois, south to Ala- 
bama and Texas. 
Geological distribution: Pleistocene; Loess. 
L[Tabitat: In the larger rivers on a muddy bottom. 
Remarks: Distinguished by its heavy, solid shell and 
peculiar channeled aperture. The species is not generally 
known to inhabit this region, being usually found farther 
south, but the specimens before the writer are certainly pon- 
derosum and they were said to have been collected in the Calu- 
met River some years ago by Dr. J. W. Velie. The specimens 
were sent to Prof. R. Ellsworth Call, the well-known student 
of this intricate genus, who wrote as follows concerning them: 
“The specimens are certainly Campeloma ponderosum, mostly 
juniors, and one about two-thirds grown. They are typical of 
that form. I seriously question that your collector found 
them in the place indicated. It willbe very interesting indeed 
to have this settled by additional specimens, which will be the 
only proof beyond doubt.” The region has been very care- 
fully searched for additional specimens but up to the present 
time none have been found. It has been admitted to this list 
