MICHIGAN ACADEMY OF SCIENCE. 119 



NOTE ON A DOUBLE SNAIL, CAMPELOMA SP. (decssa. Say.) 



(Abstract.) 



H. M. MacCurdy. 



^ While examining a number of specimens of Campeloma taken in Pine 

 River at Alma, a young double snail was found together with other young 

 snails of normal form. The double snail possessed two separate dextral 

 shells slightly smaller than the average in size for the normal shells, two 

 opercula, two pairs of eyes and two pairs of tentacles. To what' extent 

 the internal organs were duplicated or shared in common is not known. 

 The left side of the foot of each individual was closely united with the left 

 side of the other in such a manner as to bring the forward movements of 

 each individual in more or less direct opposition to the movements of the 

 other. Locomotion was thus impeded though the dominating influence 

 of one which was slightly larger than the other always determined the direc- 

 tion of movement. The snails were approximately 10 mm. in diameter 

 and lived only a few days. The unusual occurrence of such a form together 

 with other peculiarities renders the specimen worthy of a more complete 

 description. 



Alma College, Mar. 31, 1909. 



