852 The American Naturaittst. [September, 
ground-mass. Three other varieties of dyke rock corresponding to 
laurdalite are recognized. The first is granitic, and is called ditroite ; 
the second is trachytic in structure, and has been denominated foyaite ; 
while the third has phenocrysts of elzolite in a granitic ground-mass. 
This a nepheline-porphyry. Hedrumite is trachytic, but it contains no 
elzolite, or, if any, but a small quantity. A tinguaite variety of these 
rocks is also recognized. Among the acid rocks a quartz-bearing 
augite-syenite is distinguished by the nameakerite. This rock is com- 
posed of orthoclase, plagioclase, a large amount of brown biotite, 
idiomorphic diopside, nepheline, sodalite, usually olivine, and nearly 
always quartz. Its structure is granitic, and its peripheral facies is a 
quartz-porphyry. Several varieties of the rock were discovered, one, 
of which is a hypersthene-akerite. More acid than akerite is nordm- 
arkite, which is a quartz-syenite, consisting of microperthite, a diop- 
‚side pyroxene, biotite, glaucophane or exgirine, and arfvedsonite, 
sphene, and a little zircon. It is granitic, with quartz in ordinary 
granite form, Since the rock contains less than 66% of SiO, it is 
called quartz-syenite, rather than soda-granite. The corresponding 
effusive rock is a quartz-rhombic-porphyry, with a poicilitic ground- 
mass of quartz and feldspar. Soda-granite is developed in severa] 
varieties, among which hornblende, arfvedsonite, and zgirine varieties 
are the most important. The structure of the rock is not strictly 
granitic, consisting, as it does, of a ground-mass composed of short 
rectangular orthoclase, quartz, needles of ægirine, apatite, etc., with 
a few phenocrysts of microcline and egirine. The author proposes 
that the rock be called grorudite. Very many more special phases of 
these various rocks are recognized, but a full description of them is 
left to the promised monograph. The larger part,of the eae 
portion of the volume is occupied with arguments to show that 
pegmatitic veins so common in South Norway, as well as in Eus 
regions of old rocks, are true fillings of fissures by what was once a 
molten magnea. Toula? announces the results of the examination 
of rocks collected during several trips through the Balkans. The 
rocks of the Central Balkans are divided into massive rocks and crys- 
talline-schists, among the former of which granite, diorites (including 
nadel-diorite), uralite-diabase, microgranite, orthophyres, porphyrites, 
pepheline-basalt, limburgite, and andesitic and porphyritic tufas are 
described ; among the latter granitic, hälleflinta and other gneisses and 
- quartz-phyllites are mentioned. In the Eastern Balkans are fossiliferous 
sandstones and limestones and eruptive rocks, including granites, 
T Neues Jahrb. f. Min., etc., 1890, 11., pp. 263, 273. 
