PYRAMIDULA SHIMEKII {Pilsbry) Shimek. 



BY B. SHIMEK. 



In nearly all of the fossiliferous loess deposits of Iowa 

 and Nebraska there occurs a fossil mollusc which has had 

 a curious history. More that twenty years ago it was the 

 subject of earnest boyish dispute between Mr. H. A. Pils- 

 bry and the present writer, who together collected it at 

 Iowa City. For some years both Mr. Pilsbry and the 

 writer distributed it as Zonitcs limatulus Ward, under 

 which name it was also published*, and no correspondent 

 questioned the identification, although the fossil is very 

 distinct from that species. Having reached the conclusion 

 that the species is distinct, the author prepared a descrip- 

 tion and figure of the fossil in 1890, and was about to 

 publish it under the name Zonitcs pilsbryi, when he re- 

 received Pilsbry's paperf in which the same species is 

 described under the name Zonitcs shimekii! In that paper 

 Pilsbry calls attention to the fact that "except in sculpture, 

 the Z. shimekii is far more like Z. nitidus than to Z. 

 limatulus." So great is this resemblance to Z. nitidus 

 that the author once referred the fossil to that species^. 



However, the coarser sculpturing on the upper surface 



* B. Shimek: Am. Geologist, vol. i, p. 149, Mar., 1888; Bull. Lab. Nat. 



Hist. State Univ. of Iowa, vol. i, p. 61, Nov., 1888; vol. i, p. 202, 1890. 

 C. L,. Webster: Am. Naturalist, vol. 22, p. 419, May, 1888, (list of shells 



by Shimek). 

 W J McGee: 11th Ann. Rep. U. S. Geol. Sur., p. 461, 1891. 

 C. R. Keyes: la. Geol. Sur., vol. vii, p. 344; 1897. 



f Proc. Acad. Nat. Sci. Phil, for 1890, p. 297. 



i Proc. Iowa Acad. Sci., vol. v, p. 33. 



