388 IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



loess area. This may be an outlying cotony similar to some of the 

 modern ones. 



This locality lies nearly a hundred miles west of the above- 

 defined line. 



The species is rather abundant in the loess along Missouri river 

 from near Sioux City, Iowa, and Ponca, Nebraska, to St. Joseph, 

 Missouri, at some localities being more common on one side of the 

 river, and at some on the other. It also extends back from the river, 

 especially along the larger tributaries, for many miles, — in Nebraska 

 to the line indicated, and in Iowa to an irregular curve drawn from 

 Hamburg to Carroll, and thence to Sioux City and Westfield. The 

 latter curve practically forms the eastern limit of the main body of 

 the Missouri valley loess on the east side of the river in Iowa, and 

 our species has been found in every county within that area south of 

 Sioux City. 



South of the Iowa line the loess is more nearly limited to the 

 bluffs of the Missouri valley. The species is common in Atchison 

 county, Missouri, at Peru, Nebraska, and St. Joseph, Missouri, and 

 extends thence locally along the Missouri to St. Louis county, 

 Missouri. It has been reported specifically from Jackson, Howard, 

 (Sampson), Cooper (Sampson), and St. Louis counties, being desig- 

 nated as a "Pleistocene" fossil by Sampson. 



The known southern limit of the fossil form has been extended 

 along the east side of the Mississippi almost to the south line of 

 Tennessee. In the second of the writer's papers (1905) the follow- 

 ing statement occurs on pages 233 and 234 : "Owen also mentions 

 Helicina, without specific name, as occurring in Hickman, Ky. This 

 is probably H. orbicidata, as Dana reports this species from Hick- 

 man, Ky., on the authority of Wetherby, though Hickman county 

 is so near the southern limit of fossil H. occulta that it may have 

 been the latter species." Since that statement was written the writer 

 has made extensive collections of loess fossils in and near Hick- 

 man, and among them are numerous specimens of Helicina oc- 

 culta, ranging -in size from six to seven and one-half millimeters. 

 While several hundred specimens of this species were collected, not 

 a single specimen of H. orbiculata was found. The latter species, 

 if present, must be very rare, and it is possible that Wetherby's 

 report is an error. 



Not only is our species common at Hickman, but the writer 

 collected numerous specimens in Tennessee, at Dyersburg, Ashport 

 bluff, near Covington, and at Fulton. The Dyersburg specimens 

 range from six to eight millimeters in greater diameter, thus ecjuril- 



