16 
Heads of fishes too large to pack, with some of the scales, 
may be preserved in this way, when circumstances do not per¬ 
mit the skinning of the whole fish. 
Eels, and such other fish as are covered with mucous or 
slime, should be carefully washed before being placed in 
spirits.'* 
INVERTEBRATE ANIMALS, OR ANIMALS WITHOUT A SPINE OR 
VERTEBRA. 
Mollusca or Shell-Jish .—The animals themselves can only 
be preserved in spirits. The covering or shell is the part that 
will more particularly attract the attention of the collector. 
Shells may be naturally divided into those of land and wa¬ 
ter, and the latter sub-divided into salt and fresh water. An¬ 
other arrangement, quite as natural, is into univalves, (as 
snails,) bivalves, (as oysters, muscles, &c.,) and multivalves, (as 
barnacles.) 
Generally, all shells, but particularly the fresh water and 
land ones, should be collected with the animal in them alive. 
After its death, the shell is liable to lose its epidermis and in¬ 
ternal brilliancy, and thus become lessened in beauty and val¬ 
ue in the cabinet. 
The collector will find shells of some kind in almost every 
considerable body of water that has a permanent existence. 
Rivers, creeks, lakes, and ponds, as well as the sea-shore, will 
repay his labors in this branch of natural history. Some of 
the univalves will be found floating about or attached to sub¬ 
merged vegetation or other material; but the bivalves will be 
generally found in the mud or fastened permanently to rocks 
or something else at the bottom. Fresh water bivalves may 
be found in clear shallow water very readily, generally by 
their tracks through the mud; but as this is a condition of 
things not always to be expected, they must be caught by ra¬ 
king or grappling with the hand. Many shells secrete them- 
* Before packing fish or small animals in spirits, it is well to keep them immer¬ 
sed in this fluid some days. It may even be necessary to change the fluid once or 
oftener ; this necessity can be known by ascertaining whether the spirits has lost 
its flavor, or the specimens begin to show indications of decay. 
