Gross Anatomy of Campeloma. 491 
ON THE GROSS ANATOMY OF CAMPELOMA. 
BY R. ELLSWORTH CALL. 
PTa collection of a large number of specimens of Campeloma 
subsolidum Anthony, in the Des Moines river, Iowa, in early 
August, presented opportunities to somewhat carefully study the 
coarser anatomy of the genus as exhibited in this species. The 
results of this study are herein given, It may be noted, as intro- 
ductory, that an unexpected closeness of structure to that of the 
foreign genus Paludina was developed, and, further, that the gen- 
eral diagnosis given by Dr. Stimpson! will need some slight emen- 
dation, particularly in respect to certain external characters, and in 
respect to the lingual teeth and the branchial lamine. 
External Characters.—In the living and recently dead animal 
the color of the foot-mass is light lead or bluish white. Viewed 
from above, the cervical lappets, foot, operculigerous lobe, tentacles 
and proboscis are further enlivened by irregularly scattered bright 
orange-yellow dots. These dots are, on the tentacles and proboscis, 
arranged in somewhat regular transverse rows, giving a barred 
appearance to each. These last-named organs are, moreover, marked 
by an abundant deposition of black pigment immediately under 
the cuticular membrane. The under surface of the foot, the crawl- 
Ing disk, shows, in living specimens, the large longitudinal pedal 
muscles. When these muscles contract, in the act of withdrawal 
into the shell, the anterior margin of the disk is reflected upwards 
and backwards over the proboscis and tentacles. This reflected 
portion is, as a whole, then bent backwards and downwards to be 
finally covered by the posterior portion of the foot, the upper sur- 
face of which carries the operculum. The whole mass is then with- 
‘drawn into the shell. During the period of reproduction, when 
the organs devoted to that function are in a condition of marked 
activity and distension , the animal, especially of the female, cannot 
soy retracted. In this respect it resembles most of our large 
ices, 
Sexual Features.—The sexes are readily distinguished, in life, by — 
means of the right tentacle, which, in the male, is very much larger 
-than its fellow and rather more curved outwards (Plate VIL, Fig. 2% : : 
1 Smithsonian Mise. Coll., No. 144, p. 35, 1865. 
