400) = The American Naturalist. 
sketch of the geology of the Japanese Islands Harada‘ gives short des 
tions of Archean gneisses and schists, and of eruptive rocks of 
recent age. Among the schists are mentioned graphitic seri 
schists, with well-developed crystals of tourmaline and hematite, 2 
chloritic amphibolite whose principal feldspar is albite. Gabbros 
peridotites cut the Paleozoic strata. In some specimens of the fi 
piedmontite was noticed as an alteration product of hornblende. 
the Mesozoic occurs the largest quantity of eruptives. Granite 
diorite in many varieties cut through the sedimentary rocks, andc han 
ee 
contact action. The eruptives, on the other hand, become coarse- 
g and porphyritic near the contact, the diorite losing hornble de 
Among the effusives of this age are i aeniohed quartz- -porphyries 
porphyrites. Weinschenck > communicates additional info 
with respect to the rocks of these islands, as a result of the study 
some hand specimens. Most of the sections examined by him at 
a hypersthene andesite, witha plagioclase full Sf inclusions, and a ple 
trachyte containing biotite, garnet, and tridymite in a ground-mass- 
the same minerals and zircon, in a trichitic glass. The most interest- 
ing rock of the series bears the same relation to the andesites as 
augitites do to the basalts. It consists principally of acicular 
of bronzite in a ground-mass consisting of clear glass and magnetit 
grains, with porphyritic plagioclase and garnets. The author calls 
= rock sanukite, from the province in which it is found. 
Mineralogical News.—The regular silicates are very few in m 
_ ber, and of them eight are orthosilicates,—viz., exlyite, sunyite, 
danaiite, garnet, sodalite, nosean and hauyne, and Jasurite. . 
Brégger and Backstrém® would include in one group, which 
would call the garnet group. The members of this group is divi 
two sub-groups, in one of which the tetrahedral habit is predom 
and the cleavage is octahedral. This includes the first four min 
“mentioned above, and is known as the helvite group. All its me 
can be represented by formulas of the garnet type. Helvite 
ote Japanischen Inseln., rst Lief., Berlin, Parey, 1890. 
5 Neues Jahrb. f. Min., etc., B. B. VII., p. 133. 
$ Zeits. f. Kryst., XVIIL., 1890, p. 209. 
