84 Beautiful Shells. 
his boat just about to throw his dredge into the 
sandy bottom, where he knows the .delicious testa- 
ceans do, or ought to, lie most thickly. The dredge, 
which is a triangular iron frame with a net over the 
bottom, will naturally sink, and when the line to 
which it is attached ceases to run out, the dredger 
will put his boat in motion, and draw it thus over 
the Oyster-bed, and then pull it up filled, it may be, 
with little fat “ Miltons,” or large ‘ Colchesters,” 
or such other kind as the spot is known to yield. 
The Latin for Oyster is Ostrea, and that is a 
name given to a genus of the Pectinide family, 
comprising beside the O. edulis, or common Oyster, 
many other species. Hdulis means eatable. Some 
naturalists divide these Ostraceans into two groups, 
first with simple or undulated, but not plaited 
valves; second, those which have the borders of 
their valves distinctly plaited. 
To the first group belong the Common Oyster, 
and between thirty and forty other living species, 
which are found principally in warm and temperate 
latitudes. In the Polar ocean none have been 
discovered, and in the hotter climates they are 
most abundant, being found in large beds or banks 
near the coast, and often attached to rocks, and 
even to trees which grow by the water, so that the 
