358 The American Geologist. December, L903 
less, but regard for scientific truth makes the exhibition im- 
perative. 
Granting for the sake of argument that the Lansing deposit 
is true loess, — though the difference of opinion among those 
who have examined it makes this extremely doubtful, — if it can 
be shown that aquatic shells of the fluviatile types, or at least, 
types of aquatic shells other than such as inhabit 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 tor 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 thmi 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 shells of aquatic species ; — and the result of these efforts 
has been that no fluviatile shells were found in undoubted loess, 
the aquatic species, comparatively insignificant in number, be- 
ing all such as are known to conchologists 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 
durin iS many weeks, or even months, each year. This negative 
evidence is not conclusive excepting as to one point, namely: 
that fluviatile shells are extremely rare, if not wholly wanting, 
in the loess, "f That modern fluviatile shells may occasionally 
be transported to higher grounds without floods has also been 
shown by the writer. $ 
*Proc. Iowa Acad. Set., vol. v, pp. 32-45. 1898; vol. vi, pp. 98-113, 1899; 
Jour. Oeol., vol. vli, March, 1899; Hull. Lub. Nat. Hist. State Univ. of 
Iowa, vol. v. Mi. 195-216, 1901, (reprint A.m. Gbol., Dec. 1901); Am. 
Gkol.. vol. xxx. pp. 280-298, 1902. 
tThe writer has collected a few fluviatile T'nios at Sioux City and Ham- 
burg, 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 1'nios from a deposit in Plymouth county. Iowa, which he does 
not consider true loess. See Iowa Oeol. Stir., vol. viil, p. 340. 
Xl'rcc. la. Acad. Boi., vol. v, p. 37, 1898. 
