248 The A mi ricti ii Geologt8t October, 1893 
It is ;i desirable article for the production of sulphurous acid, 
and is used also by smelters to add to charges which require 
more iron sulphide. 
In the operation of hand-sorting and culling the blende 
from the rock and pyrites (much of this work being done 
with the hammer), considerable quantities of "smalls" or 
chips are made from which the blende cannot be separated by 
hand. There are also large deposits of mixed blende and 
pyrites where the two minerals are so mingled that they can- 
not be separated by culling. In fact, the deposits of zinc- 
blende in heavy sheets free of pyrites or sufficiently so to be 
made available as a commercial product by hand-sorting are 
rare, and even in such mines there are portions which are 
avoided or left standing because separation cannot be effected 
even in a mill. For in milling and concentrating zinc-ores as 
they come from such deposits, while it is feasible to separate 
thoroughly any rock or flint, and also to take out the much 
heavier galena, a concentrate is obtained which carries not 
only the blende but the pyrites which was present. Such con- 
centrates are not fit to use for the production of spelter and are 
not marketable. The treatment of such concentrates for the 
separation of the pyrite and the production of a clean high- 
grade merchantable zinc-blende is the subject of another pa- 
per. — Trans. Am. Inst. J/7//. Eng. 
A NEW CYCAD. 
By T. H. McBride, Iowa City. 
Plate XI. 
In 1868, Mr. W. Carruthers described under the generic 
name Bennettites certain fossil cycadaceous plants from the 
Lower Green Sand of the Isle of Wight.* The most striking 
and apparent features of the genus Bennettites would seem to 
be its elliptical outline and the circumstance that the flower 
buds arise irregularly from the inner bark and among or be- 
tween the leaf-bases. Certain fossils obtained by the writer, 
near Minnekahta, in South Dakota, seem not only to belong 
* See Trans. Linmean Society, Vol. 2C, p. G75 eeq. London, 1868. 
