1894.) Geology and Paleontology. 511 
Geological News.—GENERAL.—In regard to the term gneiss, 
Professor T. C. Bonney remarks that it covers a group of rocks rather 
different in character and very different in history. One (a common 
type) is a gneiss in consequence of an original structure, and remains 
very nearly in its original condition. Another (also conimon) owes its 
‘structure to pressure acting on a rock which had already solidified 
and had become erystalline. The Central Oberland and some parts of 
the Pennines afford examples. A third (rather rare and exceptional) 
is the result of the metamorphism of materials which were originally 
clastic. Such has been the origin of some of the banded gneisses in 
Sark, and more evidentally in a mass of rock near the base of the 
Allalin glacier where veins of intrusive granite exhibit a banded 
3 structure which can only be explained by a movement of the material 
i while still in a plastic condition. (Geol. Mag., March, 1894.) 
ArcHEan.—According to Mr. Robert Bell, many of the long 
straight valleys in the Archean regions of Canada now oceupied by 
river stretches, by long, narrow lakes, and by inlets of larger lakes 
are due to the decay and removal of wide greenstone dykes, together 
with belts of rocks between them. The writer instances the inlets of 
the northern part of Georgian Bay, Onaping Lake, Long Lake, Sepi- 
wesk Lake with Nelson River, Mattagomi River and Lake Temiscam- 
ing. The latter is from one to two miles wide and has a length of 35 
miles, but the channel is continued into Deep River. The writer esti- 
mates the depth of this excavation to be about 2,600 feet. Mr. Bell 
presents stratigraphical evidence to show that this valley existed 
before the date of the Niagara formation, and he believes that most of 
the valleys which mark the courses of the decayed dykes were formed 
before the deposition of the Paleozoic strata. (Bull. Geol. Soc. Am., 
Vol. 5, 1894). 
Dr. U. S. Grant concludes, after study in detail of the granitic area 
near the eastern extension of the Mesabi range in Minnesota, that the 
rocks of this region are not altered sediment as has been thought here- 
tofore, but that they are truly eruptive in nature and origin. They 
are sharply separated from the surrounding clasties, and of later date 
_than those. (Ann. Rept. Minn. Geol. Surv. for 1892). 
Parrozorc.—Among the Silurian Trilobites described by Messrs. R. 
_ Etheridge, Jr. and John Mitchell in Proc. L. S. N. 8. W. pee 
March, 1894, are three new species: Cyphaspis yassensis, C. horani an 
