440 The American NaUiralist. [May, 
coarsely laminated, a soft chloritic or micaceous material, al- 
ternating with layers of a hard, compact, non-foliated stony 
substance. The hard layers consist of calcite and feldspar in 
a mosaic of feldspar, chlorite, calcite, muscovite, secondary 
quartz, epidote, biotite, and iron compounds. The softer 
strata contain a great deal of chlorite and epidote is present, 
the other constituents remaining the same. The epidote is 
thought to have originated before the development of schistis- 
ity in the rock. Both layers have practically the same com- 
position, and are therefore regarded as parts of the same 
magma. Both show evidences of the result of pressure in the 
case of their individual components. Only in certain portions, 
however, (in the softer layers) has this pressure produced foli- 
ation. — Ascension Island in the South Atlantic Ocean is en- 
tirely of volcanic origin. Its rocks embrace principally 
trachytes and andesites. The most widespread and the oldest 
of these, according to Renard,' is a pyroxene trachyte with a 
glassy base, which is locally so largely developed as to yield 
a trachyte-obsidian. In both phases little microlites of ortho- 
clase are twinned according to the Carlsbad law, showing in- 
terpenetrative crosses in the thin section. By the assumption 
of hornblende the rock passes into a hornblende-trachyte, and 
by the local accumulation of silica a transition into rhyolite is 
noticed. The surface of the island is covered with scoriaceous 
basalts. In some localities an andesite occurs in which the 
augite is bronzite. Over several circumscribed areas the vol- 
canic rocks contain, as inclusions, fragments of granite, diabase, 
and gabbro. — A few notes on the rocks occuring in the aurifer- 
ous tracts of Mysore Province, South India, are communicated 
by Burney' as an appendix to an article by Attwood on the 
structure of the region. The rocks embrace eclogites, horn- 
blende, and mica schists, all showing evidence of the effects of 
great pressure and also dykes of various eruptive rocks. The 
gold is found in quartz veins in the schists. — An interesting 
trachyte' from the Cumana railroad tunnel, near Naples, Italy, 
contains sanidine, two varieties of hornblende, and rod-like 
aggregates of hornblende and pyroxene in a ground mass of 
sanidine, amphibole, and magnetite. In the vesicles of the 
rock are large, colorless pseudo-hexagonal crystals of sodalite, 
rods of black amphibole, pyroxene, little crystals of sanidine, 
' Bull. Mus. Roy. d. Belg. T. v., No. i, p. 5. 
"- Quart. Tour. Geol. Soc, Aug. 1888, p. 636. 
' Johnston. Lavis: Geol. Magazine, Feb. 1889, p. 74- 
