1880. ] Geology and Palecntology. 907 
known types, ancient or modern; and some of them appear to be 
even more complicated than their nearest living allies. 
“We appear, therefore, to be no nearer the beginning of things 
in the devonian epoch than in the carboniferous, so-far as either 
carboniferous types in support of any special theory of the origin 
of insects. 
“ Finally, while there are some forms which, to some degree, 
bear out expectations based on the general derivative hypothesis 
of structural development, there are quite as many which are 
altogether unexpected, and cannot be explained by that theory 
without involving suppositions for which no facts can at present 
be adduced.” 
America’s Coat Suppty.—Mr. P. W. Sheafer, of Pottsville, 
writes as follows respecting the supply of coal of the United 
States, and the methods of mining it: The coal resources of 
Great Britain are all developed now, and in process of depletion ; 
whilst in this country when our four hundred and seventy square 
miles of anthracite are exhausted, we have more than four hun- 
dred times that area, or 200,000 square miles of bituminous, from 
which to supply ourselves and the rest of mankind with fuel. The 
coal product of the world is about 300,000;000 tons annually. 
The North American continent could supply it all for two hun- 
dred years. With an annual production of 50,000,000, it would 
require twelve centuries to exhaust the supply. But with a uni- 
form product of 100,000,000 tons per annum, the end of the bitu- 
minous supply would be reached in eight hundred years, What 
the annual consumption will be when this continent supports a 
teeming population of 400,000,000 souls, as will be the case some 
day, must be left to conjecture. But with half that population, 
as energetic, restless and inventive as our people in this stimula- 
ting climate have always been, under the hopes of success, such a 
country as this constantly holds out to tempt ambition and reward 
enterprise, it is a very moderate estimate, guided by the actual 
output already reached in Great Britain, to suppose that there will 
be ample-use for one hundred pei tons a year of bituminous 
coal for home consumption a 
We have about three hundred ae forty oe and produce 
h 
20,000,000 tons per annum, or about 60,000 tons each. Great 
Britain has nearly four thousand collieries, and ines 132,000,000 
tons, or 33,000 tons per colliery. The greater the yield per 
colliery the less the expense in mining. If we decrease the num- 
ber of mines and increase their capacity not only to raise the coal, 
but to exhaust a constant current of foul air and dangerous gases, 
clouds of powder smoke and millions of gallons of water, we will 
reduce the cost of mining. Most of the anthracite mining in the | 
United States is now done at a less depth than five hundred feet 
