448 TROPICAL NATURE VIL 
coveries should have been made in California rather than in 
any other part of America is sufficiently apparent if we consider 
the enormous amount of excavation of the Pliocene gravels in 
the long-continued prosecution of gold-mining, and also the 
probability that the region was formerly, as now, characterised 
by a milder climate, and a more luxuriant perennial vegetation, 
and was thus able to support a comparatively dense popula- 
tion even in those remote times. Admitting that man did 
inhabit the Pacific slope at the time indicated, the remains 
appear to be of such a character as might be anticipated, and 
present all the characteristics of genuine discoveries. 
Concluding Remarks on the Antiquity of Man 
Even these Californian remains do not exhaust the proofs 
of man’s great antiquity in America, since we have the record 
of another discovery which indicates that he may, possibly, 
have existed at an even more remote epoch. Mr. E. L. 
Berthoud has described the finding of stone implements of a 
rude type in the Tertiary gravels of the Crow Creek, Colorado. 
Some shells were obtained from the same gravels, which were 
determined by Mr. T. A. Conrad to be species which are 
“certainly not later than Older Pliocene, or possibly Miocene.” 
The account of this remarkable discovery, published in the 
Proceedings of the Academy of Natural Sciences of Philadelphia, 
1872, is not very clear or precise, and it is much to be wished 
that some competent geologist would examine the locality. 
But the series of proofs of the existence of man by the dis- 
covery of his remains or his works going back step by step to, 
the Pliocene period, which have been now briefly enumerated, 
takes away from this alleged discovery the extreme im- 
probability which would be held to attach to-it at the time 
when it was made. 
It is surely now time that this extreme scepticism as to 
any extension of the human period beyond that reached by 
Boucher de Perthes, half a century ago, should give way to 
the ever-increasing body of facts on the other side of the 
question. Geologists and anthropologists must alike feel that 
there is a great, and at present inexplicable, chasm interven- 
ing between the earliest remains of man and those of his 
animal predecessors—that the entire absence of the “ missing 
