988 General Notes. [October, 
gneiss, etc., of the first series is supposed to be Laurentian, while 
the quartzite schists and limestones, etc., of the second series are 
Huronian. The latter series is the great mineral repository of 
Brazil. Here occurs the schistose micaceous quartzite called 
iron and extensive beds of hematite and other iron ores, and gold. 
Tapanhoacanga, consisting of masses of iron ore cemented by 
limonite, is often very rich in gold. The Serra do Espinhaço is 
capped with sandstone believed to be Silurian, and probably a 
part of the sandstones of the Sao Francisco-Tocantins divide are 
also Silurian. The tablelands of the Parana basin, composed of 
sandstone and shale with some limestone, are probably Devonian 
and Carboniferous. Devonian fossils characterize an extensive 
area in the Campos Geraes de Parana, while the Carboniferous 
covers a large region farther to the westward in the same province, 
and in Sta Catherina, Rio Grande do Sul and Southern and West- 
ern Sao Paulo. Coal has been found at various points. Immense 
dykes of diorite traverse these two formations, and by their de- 
composition afford a dark red soil called zerra rova—O. A. 
Derby (Am. Four. of Science, Sept., 1884) shows that the flexi- 
bility of itacolumite is only a surface quality. In a cutting upon 
the Rio and Minas railroad (Brazi!) a thickness of forty meters of 
itacolumite is laid bare. The upper portion consists of massive 
beds from one to three meters thick, in which flexible portions 
are rarely found. In the lower part the beds readily divide into 
thin laminz, most of which are more or less flexible. Exposures 
of unweathered itacolumite are rare, and from the study of this 
Mr. Derby concludes that flexibility is not an original character- 
istic of the rock but a phase of weathering brought about by per- 
colating waters. 
Stlurian.—Sr. Leon Tourquist has published descriptions of 
113 species and varieties of trilobites discovered in the Silurian 
basin of Siljan, in Dalecarlia. The descriptions mainly rest on 
detached heads and pygidia, as the fossils are fragmentary. 
Carboniferous.—S. H. Scudder has described two new Carbon- 
iferous insects from England. One of these can with certainty 
be referred to Brongniart’s group of Protophasmida. The wing 
is broadest in the middle, and from the appearance of the frag- 
ment, which is 75™™ long, must have had a length of 130 ™ So | 
that the living insect probably possessed an expanse of wing of at 
least ten inches. 
=~ _ Cambrian.—Mr. W. O. Crosby (Proc. Bos. Soc. Nat. Hist.) de- 
_ fends his previous conclusions respecting the relations of the 
_ conglomerate and slate in the Boston basin. He maintains that 
_ the conglomerate underlies the slate, that there is essentially but 
one formation of conglomerate and one of slate; that both are 
nordial, or at least Cambrian, and that the Boston basin con- 
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