412 DIRECTIONS FOR COLLECTING 
out, the shells remaining. The -shells may be emptied into 
the bucket of water, and the dredging continued as Jong as 
desirable. For more rapid progress in collecting, a net made 
of iron wire-gauze, of about twelve to sixteen wires to the 
linear inch, is very useful (Fig. 2). The gauze may be 
stretched over a stiff metal- 
4 lic frame, so arranged as to 
form a bag, the mouth of 
which is about eight inches 
by four, with a depth of 
about eight inches. The net 
should be fixed at an angle 
of 45° with the handle. 
The outer margin (at the mouth of the bag) should have & 
sharp metallic edge like a hoe. A long handle is necessary ; 
one that may be separated into parts, each about three bie 
four feet long is most convenient, on account of the facility 
of adapting the length of the handle to the depth of the 
water, or to the position from which the collector has to 
work. 
With a properly arranged apparatus of this kind, nearly 
all the small univalve and bivalve aquatic species may be 
secured with more readiness and in greater abundance than 
by other means. The shells that cannot be so readily ob- 
tained in this way are the fresh-water limpets ( Ancylus 
and Gundlachia), which have to be taken by the slow pr°- 
cess of removing them simply from the stems of plants = 
surfaces of stones to which they adhere, by sliding à knife- 
blade under them. , 
Many small species of fresh-water mussels ( Unio 
such as are sometimes found abundantly in seme 
Southern and Western rivers, are often readily attam 
means of the net. By proper manipulation the ee 
made to scrape up a thin or thick slice of mud with the 2 
that. mingle with it. Then reversing the net in the wa = 
mouth upward, the sand and fine mud are sifted out, @ 

nide), 
of the 
able by 

