PROCEEDINGS OF SOCIETIES. 
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the abundance of tangles or sea-weeds of the genus Laminaria which flourish 
in it around the shores of Europe. On sandy ground these are replaced by the 
grass-wrack or Zostera. Vegetable-feeding shell-fish and naked mollusca are 
exceedingly numerous in this space. Its usual vertical extent may be stated to be 
between low-water mark and fifteen fathoms (90 feet). Owing to the depth of the 
Laminarian Zone, no mollusca can be obtained from it except by dredging ; and 
here, for the sake of those who are not quite masters of this subject, I may add a 
few words about the dredge itself, and of how and where to use it. 
There are several kinds of dredges, but the one that is now universally used 
is called the naturalist's dredge , first recommended, many years since, by Dr. Ball. 
It consists of an iron, rectangular frame (if the iron be galvanized it will resist 
the action of the sea-water better)—13 inches by 3 will make a convenient-sized 
dredge; but, of course, it can be made of any size; a scraper is attached to each 
side, having a bag attached in the usual manner. This bag can be made of spun 
yarn, or of fishing-line, netted with a small mesh, or, what is best of all, when it 
can be obtained, raw hide, cut into fine thongs, and netted in like manner. The 
meshes might be three-fourths of an inch at the iron rim, and diminish to one- 
fourth at the end of the bag; but there should always be a free current of water through 
it while the dredge is on the bottom, or else it only acts as a scraper, driving every 
thing before it and coming up empty. The handles of the dredge are moveable, 
and are nearly the length of the frame, so as that they may both lie evenly in the 
space between the scrapers of the dredge ; to each of the handles is attached half a 
dozen links of a chain, which are connected by a plain ring, to which the rope is 
attached ; the flexibility of the chain increases the biting power of the scraper. 
The dredge may be thrown out of either the stern or side of the boat; and it will 
economize time, if to the same rope two dredges be attached ; so that while one is 
examining the contents of one dredge, the other may be actively employed—of course, 
as you pull up the one you let down the other; you should allow nearly thrice as 
much rope to be overboard, as the perpendicular depth would require; thus, if you 
were dredging in seven fathoms of water, you should, at least, have, over¬ 
board, twenty-one fathoms of rope, otherwise your dredge will only hop along the 
bottom. In case the dredge gets fast in a rock, or in a large Laminarian forest, it 
is advisable to reverse the rowing, so as to pull contrariwise to that in which the 
dredge has been entangled, and this will generally succeed in getting it free. In 
dredging in sounds, or where currents prevail, in a row-boat, of course, you 
always row with the current; and in sailing, the boat is put before the wind—the 
inward edge of the rope, in all cases, being made fast to one of the boat’s thwarts ; 
but this should be done with great caution ; for if the dredge gets suddenly 
entangled, and the rope that connects it be good, it will be very likely to carry away the 
mast, if not upset the boat. This accident has happened in dredging in the west 
of Ireland. Eor deep-sea dredging, where there is danger of the dredge floating, 
this difficulty can be removed by affixing a weight at a short distance from its mouth. 
It is not on every coast that dredging can be practised. On some, the surf is 
habitually too great to admit of boating. On some shores no boats are to be had, 
there being no harbours where they can be kept in safety. On the west coasts of 
Ireland, for example, the broad waves of the Atlantic continually rolling in, keep 
up a troubled water, in which the pursuits of the deep-sea naturalists can rarely be 
carried on. In other places, a rocky, or, as it is technically called, a foul bottom, 
and, in other terms, fields of sea-weeds, marine forests, present insuperable 
obstacles to the use of a dredge. Land-locked bays and harbours, where a quiet 
water flows over a smooth or a shingly bottom, or lies on oyster or scallop beds, 
are the favourite grounds for the amateur dredger—not that but sometimes he will 
even face the roar of the Atlantic in the cause of science. Where large banks 
occur at a long distance from land, they greatly reward the naturalist; but require 
an absence from the shore of several days. The naturalist will frequently find, 
thrown up on the Littoral Zone, large heaps of dead shells, the proper inhabitants, 
when living, of the Laminarian or, perhaps, more frequently those of the Coralline 
Zones; by paying accurate attention to the currents which set in and about the 
heap, he will be able, in general, to trace the locality of the living shells, which, 
will be mostly found in beds. 
