H. H. Howorth—The Fauna and Flora of the Loess, = 213 
Surely these facts are absolutely at issue with the theory of Baron 
Richthofen, with the dry parching winds and dust storms which he 
invokes to explain the Loess, and I do not understand how Dr. 
Nehring can avoid admitting it. 
If we turn from this lowland zone to the upland zone, we shall 
surely have the same answer to give. 
Dr. Nehring postulates for his Steppe region, which I call the up- 
land region, that it was marked by an expanse of grass pastures 
and prairies such as are found in that nomadic paradise, the valleys 
around the Altai Mountains, and in the famous Nogai Steppes, where 
the largest cattle and the finest sheep in the world are raised on the 
most succulent grasses, and he urges that these Ilanos or grass pas- 
tures were the homes of herds of Horses, and wild Asses, of Mar- 
mots, pouched Rats, and tail-less Hares, of Jerboas, and Porcupines, 
and were invaded at times by Mammoths and other beasts from a 
differently constituted area. I see nothing to object to whatever in 
this. It seems fairly to describe the kind of country to be found on 
the southern slopes of the Ural Mountains and the inner valleys of 
the Altai. But let me ask, in all seriousness, how are these grassy 
pastures compatible with Dr. Richthofen’s theory at all? Whence, 
let me ask, are we to derive the calcareous dust? How is luxuriant 
grass to grow where dust is accumulating in the fashion he 
describes? The grass protects the subsoil from denudation by 
winds completely. How, therefore, can we derive the dust from its 
surface? Again, if dust were to bury whole carcases of Mammoths 
and other great quadrupeds so that their bones should not decay or 
become weathered, or their bodies dispersed and carried off by beasts 
of prey, or otherwise, the dust must have accumulated in great 
quantities, whence did it come in this way ? and if it came, how did 
the herbage grow, and the animals live ? 
I cannot help expressing my astonishment that Dr. Nehring 
should have burdened his ingenious and convincing arguments in 
favour of a steppe or plateau fauna in Central Europe with a theory 
which necessitates the importation there, not of the grass prairies of 
the Nogai Steppes, but rather of the bare Salt Steppes of Mongolia, 
with their occasional tufts of hard wiry grass and occasional bushes 
of the still more hard and wiry Steppe-shrub, the Lasiagratis splendens. 
Even with these Salt Steppes, as we argued before, the problem 
seems quite insoluble if we adopt Baron Richthofen’s theory, @ fortiore 
in the case of Llanos and prairies of luxuriant grass. 
One more issue. Dr. Nehring disputes my reading of the evidence 
of the Mollusca found in the Loess, and quotes against me Dr. 
Martens. Here again I must claim that my view has the support 
of the facts. He refers to Dr. Todd as if he were an exceptional 
American witness. He is quite the reverse. I have just received 
from two American friends, Professors McGee and Elsworth Call, 
both experienced authorities on the Loess and its contents, an 
elaborate paper discussing the Molluscs they have found in the 
Loess of Iowa, and their view is entirely at issue with Dr. Nehring’s. 
They contend that these shells require such humid conditions that 
