( 'orrespondeuce 
361 
The remains of Diceratherium so far Found in the White River are 
from the upper Oreodon beds (Protoceras beds of Wbrtman). The dis- 
covery of Diceratherium in. these beds may be regarded as additional 
evidence in favor of Wortman's opinion thai the top of the White 
River is the equivalenl of the base of the John Day. 
J. l'>. Hatcher. 
Economic Geology of the United States; Reply to 1>h. Penrose's 
Review. It is not a very dignified proceeding for an author to reply to 
a review of one of his own works: but there are times when dignity 
musl be sacrificed in order to place (he t rut h before the public. It seems 
to me that one of these occasions has been created by Prof. Penrose's 
review of my Economic Geology of the United States which appeared 
in the February-March number of the Journal of Geology. This re- 
view, which occupies six pages of the magazine, finds the book wholly 
bad. and so inaccurate that not a word of praise can be found excepl 
for the "publisher's work." the "good language," and "the general 
scheme in the arrangement of the subject matter." which he says is 
"logical." 
At tirst sight, the volume and virulenceof the attack led me to infer 
that many vital errors had been found: the reviewer says thai these "are 
only a few of the many that might be mentioned," like the school boy 
who found the things he was writing about "loo numerous to men t ion." 
But, upon rereading i1 and boiling it down to the actual errors, these 
are found to be very few. and hardly sufficient in number to utterly con- 
demn the work. On still further examining these the astonishing fact 
is revealed that all but two and possibly three, are errors of the reviewer! 
The purpose of this reply is to point out these errors. 
As if to crush meat the very start, Prof. Penrose devotes an entire 
page to a discussion of my use of the term "ore." the implied conclusion 
of which is that the author .of an Economic Geology does nol know what 
an ore is. He quotes my definition and remarks that it should have 
been qualified. Forthwith he gives, among others, the very qualifica- 
tion (biotite) which [ do give just fivelines below the sentence quoted. 
He tells us that many ores are common rocks: but the Century Diction- 
ary, in its definition of ore. written by a well known geologist, says: "A 
mixture of a native metal with rock or vein-stone is not usually called 
ore." The rock is gangue. "The term 'ore.' " he says, "has no scien- 
tific significance whatever," in refutation of my statement that it has. 
Had Dr. Penrose studied petrography he would probably not need to be 
told that the term ore, as I used it, is to be found in Rosenbusch's pub- 
lications, and. in English, in Teall's British Petrography, p. 52. Thus 
one page of criticism, and the one upon which most energy is devoted, 
depends rat her upon the reviewer's misconceptions than upon the au- 
thor's inaccuracies, <>n the nexl page there is a very curious criticism 
and one thai is extraordinarily unfair. He takes me to task for not s-.\\ - 
ing jusl what [ do say; as is shown bj his own quotation from mj book. 
I say that the silicates are (if litth importance as ores, and he quotes 
