GEOLOGICAL DESIDERATA. 
251 
In many lo6alities the chalk and chalk-marl present, especially along 
the foot of the chalk-downs, and at the base of chalk-cliffs, a natural 
detritus, which, by careful manipulation, is found to yield rich harvests 
of microzoa. My friend, Mr. Harris, F.G.S., of Charing, Kent, has for 
some years availed himself of the abundant store of foraminifera and 
other minute fossils which he finds in the argillaceous "chalk-detritus," 
or, more properly speaking, decomposed chalk-marl of his neighbour- 
hood ; and the plan that he has lately pursued in obtaining these pretty 
objectsfree from their tenacious matrix, is as follows : — The " detritus," 
having been dug up, is exposed for a time to the air, and then portions 
are placed for some days in a trough of water until they become soft ; 
small quantities are next put, with a large proportion of water, into a 
small harvest-barrel, which is then carefully closed with a bung-cork, and 
the outside of which is armed with bucket-flanges, as in the case of an 
ordinarj' overshot mill-wheel. Making use, as a motive power, of a 
little stream ruuniug through his meadow, and suspending the barrel 
on pivots against a miniature weir, Mr. Harris secures the constant 
revolution of the barrel, and consequently a continual churning process, 
which reduces the detritus in the barrel to a creamy consistence. The 
contents of the barrel are then poured into a long conical canvas bag, 
which is set in the stream, and by the natural flow of the water and a 
continued dipping, by aid of its handle, gradually loses the finer chalky 
material and retains a coarse sediment. Care is taken to keep the 
mouth of the bag about the surface of the water; otherwise some of the 
more valuable sediment would be washed out by the regurgitating 
current and lost. The residue is taken into the house, dried, sifted, 
and picked. 
Sometimes it is found advisable to subject some portions of the 
siftings, or of the picked specimens, to a further churning in a small 
bottle of water affixed to the outside of the water-wheel. 
GEOLOGICAL DESIDERATA. 
Bhitisu Localities of Fossil Mammalia. 
The Etutor, in opening this department of the magazine, earnestly 
asks the assistance of every true geologist. In the provinces, geologists 
must be the gatherers of materials which those resident in large cities, 
from the association with the chief talent of the day, and from their 
ready access to large collections of specimens, books, and other essential 
aids, arc placed in the best position to interpret. The generalizer in 
geological matters cannot be, to any great extent, the worker in the 
field ; and the Editor trusts that his magazine may be the link to 
associate the labours of all who are interested in the progress of Geology. 
IS'o one, in forwarding information on such points of inquiry as from 
time to time will appear in this department, need hesitate on the 
ground of any fancied inability, or on a supposition that the informa- 
tion might have been conveyed by others. It will be far better for us 
to receive it in any form, or twice over, than not at all. The informa- 
tion which wc receive we shall tabulate or condense every three 
months, or at such other periods as may be deemed most advantageous. 
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