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Page:Popular Science Monthly Volume 21.djvu/626

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THE POPULAR SCIENCE MONTHLY.

adventure. There are other lizards which have a similar power, though in less degree. The American glass-snake, so called, is one.

Semper describes certain snails of the Philippine Islands which do the same thing: u Every species (Helicarion) that I personally examined possessed the singular property ... of shedding their tails when they are seized somewhat roughly, at a little way behind the shell. This they do by whisking the tail up and down with extraordinary rapidity, almost convulsively, till it drops off; if the creature is held by the tail it immediately falls to the ground, where it easily hides among the leaves. ... These snails at first constantly escaped me and my collectors in this way, and not unfrequently we had nothing but the tail left in our hand."

 

BRAZILIAN DIAMONDS AND THEIR ORIGIN.
By M. H. GORCEIX.

THE discovery of the diamond-beds of the Cape of Good Hope, with the extraordinary abundance of their yield, seems to have caused it to be forgotten that the empire of Brazil only a few years ago had the monopoly of that precious stone, as it still has of the finest crystals. Hopes have been entertained that the examination of the green serpentine, in which the Cape diamonds are scattered, would permit a determination of its origin and its primitive bed. No doubt, however, now exists that the magnificent crystals incased in that rock were already in existence when in its upward course from the depths of the earth it brought them along with it and left them where they are now found. Unless, then, new discoveries are made at the Cape, of beds of a different nature, it will be necessary to look to Brazil for the solution of the question of the primitive bed, the origin and the mode of formation of the diamond—a triple problem which appears, down to the present time, to exist as a challenge to all who are occupied with geology and mineralogy.

The diamond has been and still is mined at numerous points in Brazil, which are situated chiefly in the provinces of Bahia, Goyaz, Matto Grosso, Paraná, and Minas Geraes. Except in the last province and in that of Bahia, they give occasion only to the labors of isolated diamond-workers, the garimperos of Brazil, who wash the sands of the streams in large wooden bowls. The principal diggings in Minas Geraes are grouped around the city of Diamantina, which is situated almost on the meridian of Rio Janeiro, about five hundred miles from the coast. A few other districts also furnish small quantities of diamond. We shall consider especially the diamond-beds of Diamantina; and we need not then speak of the others, for they are all so