140 The American Geologist. February, is97 
"2. An acid volcanic rock which shows all phases of crystallization, 
from a spherulitic rhyolite to a true quartz-porphyry, is amygdaloidal 
or compact, is accompanied by pyroclastics and breccias^ and is some- 
times sheared into a perfecty fissile shale or sericite-schist. 
"3. A basic, holocrystalline, volcanic rock which is usually amygda- 
loidal, massive or more frequently schistose, and is also accompanied by 
pyroclastics and breccias and sheared to a slate." 
The various conditions and structui-es of these rocks are described 
with clearness and acumen, as might be expected of a young geologist 
who had received a petrographic training from the lamented Williams. 
Nos. 2 and 3 above are the types that cany the crucial characters, 
and the most of the e.osay is devoted to the description of their peculiar- 
ities. The acid eruptives which are the "primal upper slate" of Rogers, 
range in color "from a brick red, through pink, purple, blue, gray to 
ashy-green, light green or buff." They are sometimes porphyritic, 
spherulitic and eutaxitic. They are occasionally amygdaloidal. They 
contain flow breccias and tuff breccias. 
The basic eruptives are more widely extended than the acid, consti- 
tuting the rock of many of the valleys, foothills and mountain flanks. 
Originally massive, they have Vjecome schistose or slaty V)y pressure and 
shearing. They exhibit a marked and frequent amygdaloidal structure. 
They also contain bands and beds of volcanic ash in which are also vol- 
canic bombs. In one instance an agglomerate is mentioned, consisting 
of rounded fragments from an inch to six inches in diameter. These 
characters are fully identified and described, and thei-e can no longer be 
any question as to the nature of these "primal slates," whether of the 
upper or the lower series. 
The characters of these rocks, as noted above, as well as their well 
known content of metallic copper, and their stratigraphic position, af- 
ford so perfect a parallel with the Kevveenawan of the lake Superior 
liasin that their identity in age with the great copper-bearing formation 
of lake Superior can hardly be questioned. It is really a surprising com- 
mentary on the comparative thoroughness and skill with which the two 
regions have been examined to note that the true character of these 
"primal slates" has been detected only within recent years (Dec. 1892), 
whereas the igneous nature of the lake Superior eruptives has been 
known since about 18i2, an intervening period of fifty years, indicat- 
ing the backwardness of the geology of the Appalachians. 
In conclusion we desire here to commend the suggestions of the au- 
thor as to the nomenclature suitable for such acid rocks, viz., a devitri- 
fied rhyolyte, obsidian or perlite becomes aporhyolite, apobsidian, apo- 
perlite, the prefix apo having a significance co-ordinate with nieta and 
epi in petrographical nomenclature. n. h. w. 
The Relation of the Fauna of the Ithaca Group to the Faunas of the 
Portage and Chemung. By Edward M. Kindle. Bulletin No. 6, vol. 
II, Bulletins of American Paleontology, Ithaca. N. Y., contains 54 pp.. 
with map, plate and illustrations. The subject is treated under four 
parts. 
