Gross Anatomy of Campeloma. 491 



ON THE GROSS ANATOMY OF CAMPELOMA. 



BY R. ELLSWORTH CALL. 



fTHE 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 1 will need some slight emen- 

 dation, particularly in respect to certain external characters, and in 

 respect to the lingual teeth and the branchial lamina. 



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 

 be wholly retracted. In this respect it resembles most of our large 

 Helices. 



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 VII., Fig. 2, 



1 Smithsonian Misc. Coll., No. 144, p. 35, 1865. 



