Editorial Comiiient. 2 5 5' 
lithological characters and unlike successions. Because of the absence 
of a well-known pre-Cambrian fauna it is impracticable at present to 
make correlations in far-distant regions. Hence the term Algonkian 
has been proposed by the United States Geological Survey to cover the 
whole of the pre-Cambrian elastics. No working geologist in America 
now holds the indivisibility of the pre-Cambrian in all regions. 
If the foregoing conclusions are correct, the invariable succession ad- 
vocated by Hunt, evolved almost wholly within the laboratory, is value- 
less. It is shown to be untrue at one or more fundamental points by the 
observed order of the rocks in every region in which there are tolerably 
full successions. 
Prof. R. Pumpelly confirmed the observations of Prof, Van Hise in so 
far as he had been over the ground mentioned. He referred especially 
to observations made in the Green mountains, where in one locality 
metamorphism has completely masked the original character of the 
rocks, and thus rendered impossible correlation by lithologic characters, 
As an example he cited a formation which is a quartzite, at one point, 
a white gneiss containing new feldspars at another, a conglomerate with- 
out any schistose structure at another, and a mica schist at a fourth 
locality. 
Prof. Chas. Barrois, referring to the remarks of Prof. Van Hise, said 
that there was no general basis, either biologic or lithologic, for the 
correlation of the pre-Cambrian rocks of Europe with those of North 
America; even the terms applied to these rocks were liable to be mis- 
understood. Certainly the divisions used in France cannot be correlated 
with those now used in the United States. General correlation cannot, as 
yet, be based upon non-conformities; autopsy is the only basis upon which 
a comparison can be instituted. He pointed out certain parallelisms 
between the histories of the crystalline schists of America as illus- 
trated by Mr. Pumpelly and the gneissic rocks of Brest, where the Cam- 
brian slates are altered to gneisses of Arch;ean aspect, while the alternat- 
ing fossiliferous quartzites are changed to crystalline (juartz. Geologists 
must see the beds together in order to reach a common understanding of 
the crystalline rocks. 
Dr. Chas. A. White was called upon, but in view of the divergence of 
the discussion from the topic as originally taken up, excused himself 
from speaking upon the subject. 
Prof. E. D. Cope discussed the question from a general point of view 
with especial reference to the value of vertebrates for purposes of corre- 
lation, particularly for intercontinental correlation. He pointed out that 
there is a marked difference in the present vertebrate faunas of conti- 
nents, and that tlie variation of such forms must be sought in vertical 
rather than in horizontal ranges. Such study shows that we have had 
invasions of a given region by a fauna from without; for example, a 
South American fauna invaded North America at one time and then 
retreated, while a North American fauna once invaded South America 
and traces of it still remain in that country. He is inclined to believe 
that certain vertebrate forms did not spread over the earth from a single 
