The Lcess and its Fossils. 203 



Helicodisciis lineaijis, (Say) Morse. Not common. Fossils 

 from Bremer, Dubuque, Scott, and Johnson counties, Iowa 

 were compared with recent specimens from Nebraska, Iowa, 

 Illinois, Ohio, and Vermont. No notable difference was 

 discovered. 



The species now occurs throughout tiie United States. 



Patula strio-Qsa coofcri^ W. G. B. Not common. Fossils 

 from Johnson and Polk counties, Iowa were compared with 

 recent specimens from Idaho, Montana, and Wyoming. 



I'he fossils are much smaller than most of the recent shells 

 which were examined, those from Mullan, Montana (altitude, 

 5,600 feet) alone approaching them. 



This form occurs at present from Colorado to Montana. 



Patula alter )iata, (Sa\-) Binn. Not common. The fossils 

 from Pottawattamie county, Iowa, closely resemble recent 

 shells from Northern Michigan, though rather smaller. The 

 Polk county, Iowa fossils are still smaller. The recent shells 

 from Nebraska, Iowa, Minnesota, Illinois, Tennessee, etc., are 

 uniformly larger than the fossils. The small number of spec- 

 imens of the latter however render all estimates of variation 

 unsatisfactory. 



The species occurs at present over all the eastern portion 

 of the United States, and north to Labrador. 



Patula striatclla, (Anth.) Morse. Very common. Fossils 

 from all of the localities mentioned in the foot-note on page 

 200, were compared with recent specimens from Iowa, Min- 

 nesota, Michigan, lUinois, Ohio, and New York. The vari- 

 ation in size is but slight, and there is no appreciable difference 

 between the recent and fossil shells in this respect. 



Fossil eggs of this species are not uncommon. These were 

 compared with recent eggs from Iowa City. Those from 

 Lancaster county, Nebraska are smaller than the recent spec- 

 imens, those from Johnson county, Iowa equal them, while 

 those from Cuming county, Nebraska are larger. 



This species is now distributed from Virginia to Kansas, 

 and northward. 



