BIVALVES. 19 
attached to the tails of fish, floatmg wood, &c. 
We see in this a provision for the dispersion of 
these sedentary bivalves. Nothing is known of 
the history of the embryo from this stage until 
it assumes the form of the adult. 
As the Swan Mussel (Anodon cygneus) may be 
more within the reach of many of my readers, I 
would inform them that it does not possess a dis- 
tinct lunule nor inter-locking teeth, nor are the 
muscular impressions so distinct; but in all other 
respects it resembles Unio. 
The Food of bivalves consists of infusoria, 
diatoms, and vegetable matter, brought to the 
mouth by the portion of the branchial current, 
which is projected in that direction. 
Collecting, Sc.—The majority of the Conchi- 
fera live buried vertically in the mud: they may 
be collected by dredging with a kind of perforated 
tin saucepan, about six inches across, and fur- 
nished with a hollow handle, so as to receive the 
end of a stout walking-stick. 
After making a scoop with the tin, it should 
be shaken, keeping the mouth just above the 
surface of the water, for fear of washing out any 
of the shelly contents; by this means the mud 
and fine sand pass out through the perforations 
of the tin, and the shells and gravel are retained. 
The large shells may be bagged, the smaller ones 
placed in glass bottles or tin boxes. To prepare 
c 2 
