110 MOLLUSCOUS ANIMALS. 
the ring: attached to the point of the dredge, anotler cord is 
attache to the middle of the rod, bc, by a knot which em- 
braces the rod bc, the perpendicular branch A D, and the 
small cress-bar Df at the point where they unite. When the 
boat has reached the place of fishing, the dredge is thrown 
out at the stern in the same manner in which an anchor is 
thrown out, the last named cord serves to keep the dredge in 
its place, the plate being turned below till it arrive at the bot- 
tom of the sea, and to prevent it from being overturned by the 
way. When the dredge has reached the bottom, it is hauled 
along by rowing and sailing. Should the dredge be stopped 
by any rock or irregularity at the bottom, the rope attached to 
the ring should be pulled. When the bag is supposed to be 
full, the dredge is drawn on board by the capsian, and the 
bag is emptied of its contents, 
Different species of sea weed are frequently covered by mi- 
nute shells,—weeds should always be carefully examined. 
Many of the smaller and microscopic shells are found at high 
water mark among the fine dross and drified fragments of 
shells; this sand should be brought home and examined at 
leisure. To facilitate the process, a small wire-cloth sieve 
should be made, of about six or seven inches square, and all 
the sand sifted through it, and the shells left. See plate V., 
fig. 7. 
MOLLUSCOUS ANIMALS. 
Many species of worms, and other soft invertebrate animals, 
are to be caught also by the dredge. There is no way of pre- 
serving these animais except by putting them in spirits. Ani- 
mals of this kind are still very imperfectly known; notwith- 
standing the researches of Lamarck, Poli, and other celebrated 
naturalists. Every opportunity should, therefore, be embraced 
of bringing them home ; indeed, we are still little acquainted 
with those which inhabit our own seas. Colonel Montagu and 
Dr Grant have, however, thrown much light on this depart- 
ment. 
When animals of this kind are procured in foreign parts, a 
careful noting of the latitude should be taken; and il shoul: 
be stated, whether they live singly or are congregated, if they 
