Number 128 July 22, 1922 



OCCASIONAL PAPERS OF THE MUSEUM OF 

 ZOOLOGY 



UNIVERSITY OF MICHIGAN 



Ann Arbor, Michigan Published by the University 



NOTES ON THE INTERNAL LAMELLAE OF 

 CARYCHIUM 



By Mina L. Win slow 



It became evident during systematic work on some of the 

 smaller land snails of Michigan that the two common forms 

 of Carychium, C. exigmim and C. exile, approached each other 

 so closely in some cases that characters other than those 

 already used were desirable in order to separate the two spe- 

 cies more conclusively. It was suggested by Dr. George H. 

 Clapp and Dr. Bryant Walker that the internal lamellae might 

 be investigated, and accordingly shells of both species were 

 opened, with the results stated below. The difference in the 

 size and shape of the lamellae of exile and exigmim seemed 

 so marked that other forms were opened to see whether the 

 folds bore out the external differences of the shell upon which 

 the species have hitherto been differentiated. Some doubtful 

 forms were discovered, and some peculiarities, all of which 

 are noted in the descriptions below. All figures were drawn 



