Miscellanies. 391 
7 the surface, it was thrown away, and this crown was all that was saved. 
i - Deseription :—horizontal section of body quadrilateral, with the angles 
rounded and the sides slightly curved. The crown has two transverse 
ridges, the summit lines of which are slightly curved; between the 
extremities of the ridges on each side is a small tubercular dibiieon, 
anda mahi elevation borders the anterior and posterior extremities of 
’ the crown 
length, rer kahoey a Ess 
Size of By, { eee, Me 
| _ Length of the summit of the ridges, 0.55 of an inch. | Distance of the 
| Summits of ridges from each other, 0.42 of an inch. Height of ridges, 
0.36 of an inch. 
It is without doubt the fifth molar of the left lower jaw of a Tapir, 
_ which appears to me to be very near to the one now inhabiting South 
America, as the form and size of the tooth is nearly the same as in that 
animal, 
Jackson, La., October 19, 1841. 
. Weovoreiion of Freshwater Shells for the Cabinet—We make 
the following extract from the letter of a distinguished correspondent, 
whose shells have been in much demand among collectors, and whose 
mode of preparing them is the result of obseryation and experience. 
“ Tt is well known that these shells are composed of animal matter 
and carbonate of lime, thinly laminated. Many of them are more or 
less covered with mucus, lime, clay. and oxide of i iron, sometimes indu- 
rated, so as to require a steel instrument to remove it. Hence the first 
operation is to remove this extraneous matter by hand-brushes, and then 
with dilute muriatic acid @ remove the free lime and accidental colors ; 
then, after a thorough rinsing, and as soon as the water has dried from 
the surface, saturate the shells with the finest spermaceti oil, which 
should be left on them for several months if convenient, but wiped from 
them as clean as possible with a woolen cloth before putting them in 
the cabinet. They will then feel like steatite, and exhibit a transpa- 
rency and beauty which I could not obtain in any other way. Shells 
which have once been exposed to the air, without the animal, and have 
become thoroughly dry, can never be restored to their primitive beauty, 
because the water of the animal matter in them has. evaporated. They 
become opake, and a.slow decomposition, like that of salts, takes place, 
by the evaporation of the water of erystallization ; but the oil taking 
the place of the water, as the latter evaporates, increases the transpa 
rency of the shell, as it does that.of paper, and the superfluous oil may 
be ‘so. effectually remoyed at the proper time, that the shells. will not 
soil the fingers or smell unpleasantly ; ; but any considerable exposure 
to the air and light will soon injure their appearance.” 
