Tt \. 



The Nautilus. 



Vol. XVII. JUNE, 1903. No. 2. 



NOTES ON EASTERN AMEEICAN ANCYLI. 



BY BRYANT WALKER. 



An attempt to determine the Ancyli of Michigan leads necessarily 

 to a critical study of all the species described from the States east of 

 the Mississippi. The following notes embody the results of the in- 

 vestigation, and are published in the hope of stimulating a more 

 active interest in this most perplexing and little understood group. 



The amount of material examined has been considerable. In ad- 

 dition to that in my own collection, which includes the Jas. Lewis, 

 DeCamp and Lothrop collections, I have had the entire collections 

 of Dr. V. Sterki, Dr. R. J. Kirkland, A. A. Hinkley, Jas. H. Ferri.ss 

 and Geo. H. Clapp, and through the kindness of Dr. Pilsbry a suite 

 of seventy-three trays from the collection of the Philadelphia 

 Academy of Natural Sciences. I am also indebted to Dr. Pilsbry 

 for examining the type of Ancylus haldemani, wiiich corrected my 

 previous conception of that species, and established the validity of 

 the species described as A. kirklandi. I am also under obligations 

 to Messrs. Frank C. Baker and Henry Hemphill for valuable 

 material. 



The lack of authentic examples of many of the rarer species has 

 been a source of great embarrassment. But by process of elimina- 

 tion and careful study of the original descriptions, it is believed that 

 in most cases the difficulty has been successfully overcome. 



In studying the Ancyli well cleaned specimens are the prime 

 requisite. They can then be easily separated in tlie two sections 



