Geology and Natural History. 321 
which he says he is especially able to judge. There is nothing 
else of as much im aes ce as this, and on this point his infer- 
er is not confirm the writer’ 8 microscopic examination 
of thin wot of the sr si and rpkeien ore. No detailed 
Gefloieny of ie eisleta: in this syapenee is one “of its remar kable 
features. The sine after depreciating remarks about others 
mentions, is er, the several qualifications,—geological, 
gator of the subject; and, in contrast, the te itself contains 
no geological, sister or petrological det 
aper closes with a statement of the sahen 8 ideas as to sci- 
entific progress, part of which we cite, that the warning it conveys 
may be ie alate: and duly heeded: ‘The day seems not so far 
re sii pssing and repassing the point of truth. But, 
Strange fatality, if it s tops at this point, all is stopped, the works 
are dead. When truth is reached or discussion ends, stagnation 
ensues. Again, when the pendulum sibrates, woe be t to the man 
who swings not with it. In all a we ask geologists to stop 
and think if the eee has not swung “6 cae out of the 
y Kmmons to the Tacon 36 Beatie re especially upon what se 
a as “colonies” in these rocks , using | the hate stort as ses one 
rocks are denned to be older than, and also unc Svitoraable to, ie 
otsdam sandstone. The apparent unconformabilities were ex- 
plained by Logan on the ground of faults and displacements (Geol. 
of Canada, 1863, pp. 844-861), and this has since been the gener- 
= ac cepted view. But Mr. Marcou reaches different conclusions, 
, by means of the idea of colonies, rids the subject, to his satis- 
faotidis of adverse paleontological evidence. The Ge eorgia slates 
contain the Primordial trilobites. Le describes, as next above, _ 
the Phillipsburgh group, and this as passjng above into the Swan- 
