2o8 Natural History Bulletin. 



avara, it certainly is not the large, more eastern variety of the 

 latter species, but is identical with the form now found abund- 

 antly on the western plains from Kansas to Dakota, and here 

 referred to S. lincata. 



Sticcinca obliqua, S?Ly. Rather common. Fossils from 

 Johnson and Polk counties, Iowa, and Saunders and Lancaster 

 counties, Nebraska show considerable variation in size and 

 form. Those from Iowa, and Lancaster county, Nebraska 

 are like recent specimens from Indiana, Ohio, and Hardin and 

 Benton counties, Iowa, being more slender than typical S. 

 obliqua, and having a more elevated spire. Those from 

 Saunders county, Nebraska are larger and resemble more 

 nearly the typical recent shells from Illinois, Michigan, and 

 Johnson coimty, Iowa. The fossils however have a somewhat 

 smaller average size than the recent shells. Large specimens 

 of the preceding species approach smaller specimens of the 

 fossil S. obliqua so closely that it is very difficult to separate 

 them. 



This species, as at present found, is very variable m form 

 and size, and ranges from Arkansas to Georgia, and northward. 



Carychiuni exiguuin, (Say.) Rare. Fossils from Lancaster 

 county, Nebraska are like recent shells from Iowa and 

 Nebraska, but larger than those from Texas. The present 

 range of this species is from Texas to New England. 



L.imn<Ba ca^erata. Say. Rather common locally. Fossils 

 from Scott and Johnson counties, Iowa, and Lancaster county, 

 Nebraska were compared with recent shells from Iowa, P>lin- 

 nesota, Nebraska, and Dakota. The recent form is very 

 variable. Specimens from Minnesota and Dakota are much 

 larger than the fossils, with a larger aperture and a broader 

 shell. Those from Iowa Cit}?^ are but little larger, while those 

 from Marshall county, Iowa, and South Bend and Fremont, 

 Nebraska, are about equal to the fossils. The recent shells 

 from Lincoln, Nebraska show^ much variation, and in the 

 length and diameter of the shell, and size of the aperture 



