634 Proceedings of Societies. [ October, 
got there if it had belonged to a more recent period. But it is still 
possible that the vertebra may have been washed out of some older 
deposit by the action of rivers, and been swept down into the lake; or 
it may have been frozen into a mass of ice and been carried down by 
the river, and dropped to the bottom on the melting of the ice. The 
presence of mastodon bones with the arrow-head, in the Benton County 
case, has been accounted for in this way: The presence of the arrow- 
head proved the existence of man in the alluvial period only; but in 
this instance the arrow-head must have been contemporary with the 
older Loess deposit, and the bones of mastodon, elephant, and other ex- 
tinct species of mammalia are so abundant in this deposit, not only in 
Nebraska but throughout the Mississippi Valley, that no doubt can re- 
main that these animals were also contemporary with the Loess. 
In the instances reported by the late Dr. Koch (Tranactions of the 
- St. Louis Academy of Science, i. 61 and 117), of arrow-heads found to- 
gether with the bones of mastodon, one in the alluvial bottom of the 
Pomme des Terres River in Benton County, Mo., and the other in the 
bottom land of the Bourbeuse River, in Gasconade County, Mo., it was 
possible to explain the facts stated by him as being the result of more 
recent changes in the local alluvial drift of the river channel. Dr. Wiz- 
lizenus (Ibid., page 168) endeavored to account for all the phenomena in 
this way, and in the latter case by supposing that Indian fires had been 
built over the spot at a time long subsequent to the deposit of the bones, 
and the whole afterwards covered by alluvial overflows. He was well 
acquainted with Dr. Koch, and did not question the veracity of his 
statements. Judge Holmes had himself assisted Dr. Koch in putting 
his article into shape for publication in the Transactions, and questioned 
him minutely as to the particulars stated, and could certify that the cir- 
cumstances mentioned were positively asserted by him to be true. Nor 
had he any reason for doubting the truthfulness of Dr. Koch. As lately 
suggested by Professor J. D. Dana, it is true that Dr. Koch was not a 
thoroughly scientific and practical geologist, and perhaps he gave some 
seope to his imagination in the matter of theorizing upon his facts ; 
but he had some experience in such things, and might be allowed to be 
capable of observing the facts which he stated, however incompetent to 
apply the requisite tests for a certain conclusion. But the facts observed 
and reported were not absolutely conclusive of the matter, though carry- 
ing much weight of probability. 
In this new discovery in Nebraska we have facts well ascertained by s 
competent observer ; they are not open to the same kind of explanation ; 
and they seem to afford the necessary confirmation of the supposed con- 
temporaneity of man and the mastodon and elephant in this valley. 
Dr. George Engelmann gave ‘some results of his observations OR the 
venation of American oaks. He has observed great differences in the 
venation of different species, some having folded or conduplicate, 
eRe ae te 
