VARIOUS INVERTEBRATE ANIMALS. 
117 
Parasitic worms may be thus preserved. Wash the specimens 
with a camel’s-hair brush dipped in 10-12 per cent, solution of nitric 
acid. Place them in 40-50 per cent, alcohol for one or two days; 
then in 70-80 per cent, for seven to ten days; then in 90 per cent. 
Crustacea. 
Crustacea of all kinds are best preserved in spirit. They may be 
simply placed in it living; but, if possible, it is better to kill them 
in weak spirit (30 per cent.), and then transfer them to stronger 
spirit (70 per cent.) for preservation. 
To avoid the casting off of the appendages of the larger marine 
Decapods, they should be allowed to die in fresh-water, care being 
taken not to allow them to remain in it longer than is necessary, 
as it causes a distortion of the membranous appendages. 
Hermit-crabs should be killed in fresh-water, when they will come 
out of their shells; if killed in alcohol, it is often impossible to 
extract them without injury. The shells should be preserved with 
any commensals, as Anemones, Hydroids, etc. 
Minute and soft-bodied forms are often quite well preserved by 
simply killing them in spirit; but, when possible, it is often worth 
while to fix a portion of the catch with corrosive sublimate dissolved 
in sea-water, or in equal parts of sublimate solution and stiong 
spirit. 
Large Crabs and Lobsters can be preserved dry: their colours are 
best kept by their being dried away from strong sunlight. Specimens 
of the same species should also be preserved in alcohol. 
Formalin should, as a rule, be avoided for Crustacea. It tends 
to render the specimens brittle, and dissolves out a part of the 
calcareous salts to form a flocculent precipitate. For small and 
soft-bodied forms, however, a mixture of equal parts of 5 per cent, 
formalin and strong spirit has been employed with success. 
Fresh-water Crustacea, Crabs, Crayfish, Prawns, and the more 
minute forms are well worth collecting in nearly all parts of the 
world. Unless the collector has opportunities for dredging, or has 
experience in shore-collecting, marine Crustacea, especially the laigei 
and more conspicuous kinds, are less likely to be of inteiest. 
