Geology and Natural History. 69 
author, and a diagram presents a map-projection, after Miller’s 
method, of all known planes in their zones. “The crystals studied 
were from the Royal Mineralogical Museum of Vienna, of which 
Professor Tschermak is Director. 
9. On Atacamite; by E. S. Dana, (Zschermak’s Min. Mit- 
theilungen, Vieuna, 1874,)—The results of a large number o 
measurements of crystals of Atacamite, from Wallarro, South 
Australia, are here presented. They prove that the species is, as 
hitherto supposed, orthorhombic, but show further some irregular- 
ities in the planes of the vertical series, which can be explained 
only by the assumption of a dome 40% taking the place of 7-4, and 
a corresponding pyramid, in place of the prism I. The crystals 
under examination were placed in the hands of the author by Dr. 
A. Schrauf of the Vienna Mineralogical Museum. 
10. Changes in the character of Vegetation produced by Sheep- 
grazing.—Dr. Suaw, of the Cape of Good 0 ti 
innean Society an interesting communication (published in its 
om b 
curse to the wool-producers. In the Orange River Republic it has 
So affected the wool in some parts of the country as to make it 
nearly unremunerative as a staple product. : 
The principal changes, however, are not in the introduction of 
foreign plants, but in the alteration of the range and relative 
abundance of those that belong to the country. hen first intro- 
duced into the midland or pasturage region, the sheep fed mainly 
oe < ‘ 
the flocks, and the ground was left to them and to obnoxious and 
poisonous herbs, . . . and to the intoxicating Meliew, the 
‘dronk’ grass of the Dutch colonists.” It used to be thought that 
alee were everywhere salubrious and bland; but it appears that 
in So 
