THE LOESS AND THE LANSING MAN. 333 



insignificant pools and ponds, are extremely rare, if occurring 

 at all in the loess; and if it can be demonstrated that fresh- 

 water shells are sometimes transported to higher points by 

 agencies other than floods; then the dogmatic statements 

 quoted above fall of their own weight. 



The present writer has repeatedly called attention to the 

 absence of fluviatile shells from the loess,* giving in each case 

 specific detailed lists. He here takes the liberty to state that 

 he has searched for loess fossils north and south for nearly a 

 quarter of a century; that starting out as a believer in the 

 water theory of loess deposition he diligently sought aquatic 

 forms, and for many years would have welcomed them with 

 the same avidity with which the advocates of the theory have 

 pounced upon the Lansing Unio; that after the conviction 

 was forced upon him, against his earlier views, that the loess 

 was not of aqueous origin, he equally carefully collected and 

 preserved all fossil sriells of aquatic species; — and the result 

 of these efforts has been that no fluviatile shells were found 

 in undoubted loess, the aquatic species, comparatively insig- 

 nificant in number, being all such as are known to conchol- 

 ogists as pond-shells. The same species occur today all over 

 the loess territory in small bodies of water, — creeks and 

 ponds, — which may remain dry during many weeks, or even 

 months, each year. This negative evidence is not conclusive 

 excepting as to one point, namely: that fiuviatile shells are 

 extremely rare, if not wholly wanting, in the loess.t That 

 modern fluviatile shells may occasionally be transported to 



*Proc. Iowa Acad. Sci. , vol. v. pp. 32-45, 1898; vol. vi, pp. 98-113, 

 1899 ; Jour. Geol. , vol. vii. March, L899; Bull. Lab. Nat. Hist. State 

 Univ. of Iowa, vol. v, pp. 105-216, 1901, (reprint Am. G-eol. , Dec, 

 L901); Am. Geol., vol. xxx, pp. 280-298, 1902. 



t The writer has collected a few fluviatile Unios at Sioux City and 

 Hamburg, Iowa, in a loess-like deposit, probably washed loess, lying 

 far below the adjacent typical bluff loess, where high water might have 

 reached it. Dr. Bain reports Unios from a deposit in Plymouth county, 

 Iowa, which he does not consider true loess. See Iowa Geol. vSur. , 

 vol. viii, p. 340. 



