'889.] Mineralogy and Petrography. 523 
of magnetite. The lavas of the island of Maui and of Ohua are 
also principally olivine-basalts, in which augite is often zonally 
grown around olivine crystals. In the western portion of 
Maui is a whitish-gray compact rock, composed almost exclu- 
sively of plagioclase, with a very little altered hornblende, 
brolite and magnetite. Since it contains 61.63% of SiO, it is 
probably to be referred to the andesites. — An interesting com- 
munication by Rutley on the possible origin of epidosites 
appears in the Quarterly Journal of the Geological Society.' 
Altered felsites with a perlitic structure occur near the Here- 
ford Beacon, Malvern Hills. The rock is gray in color, and is 
traversed by a delicate network of quartz veins containing epi- 
dote grains and curved lines of epidote, which by their green 
color and strong double refraction mark out the direction of 
formerly existing perlitic cracks." The epidote is thought to 
have originated from the feldspar of the felsites, either directly 
or indirectly through the interposition of kaolin by the action 
of solutions of carbonates of calcium and iron, which would 
naturally circulate most readily through the perlitic cracks. 
By a continuation of this process epidosites might arise through 
the entire change of the material of the felsite into epidote and 
quartz. — The ejectamenta thrown out by Vulcano have re- 
cently been studied by Johnston-Lavis.' The most abundant 
products of this volcano are bombs whose surfaces are broken 
by fissures, and pieces of foreign rocks. The material of the 
bombs is obsidian, containing as inclusions pieces of basic 
rocks, and minerals resulting from these by alteration. The 
ashes accompanying these bombs consist of fragments of basic 
and acid glassy rocks, which the author believes to have been 
broken from the sides of the volcanic vent. The existence of 
pyrites in the material of the bombs, as well as the presence 
in it of olivine and augite with perfectly sharp angles, leads to 
the conclusion that the temperature of the lava from which 
the bombs were formed was low. — The obermittweide con- 
glomerate from a point in the Mittweide valley, twenty-five 
miles south of Chemnitz, has been subjected to investigation 
by Bonney,' who finds the matrix to have been derived largely 
from the detritus of a biotite granite, and to have undergone 
