66 The Echinodermata of Jdew (Brunswick. 
But many species live always below low-water mark, and to 
take such a dredge is required. The latter may be of the 
same pattern for all depths. It consists essentially of an iron 
frame, about eighteen inches long by six broad; the long sides 
are scraping jaw's of thin flat iron, somewhat diverging; the 
short sides are simply round bars connecting the scraping pieces. 
From the sides slender bars run convergingly forwards for the 
attachment of the rope, and behind drags the bag (made of 
very coarse canvas, or, better, fine netting), which is to catch 
all that is loosened by the scraping jaws."*" The dredge is to 
be dragged behind a sail boat, and the student will learn 
in a surprisingly short time all the proper methods, places, 
precautions, difficulties, pleasures and uses of dredging, which 
it would take many pages to set forth here. 
There are two principal ways of preserving Echinoderms, 
dry or in a preserving fluid. The first method is much the 
less expensive and in many ways the more convenient, but is 
not suited for specimens which are to be used for the study 
of the internal organs or other soft parts. The only preser- 
vative fluid of value is alcohol, the ordinary spirits of wine of 
the druggists. Methyl alcohol or methylated spirits, which is 
cheaper, may be used for temporary storage and the like, but 
it is not so well suited for permanent preservation of valuable 
specimens. But no specimen should be plunged directly into 
the strong alcohol from water, for great shrinkage would 
result. They should be placed first in alcohol which has been 
diluted with nearly its own bulk of fresh water, left three or 
four hours and then be transferred to the stronger grade. 
Bottles with ground glass stoppers should be used for the 
permanent preservation of alcoholic material, as they reduce 
to a minimum the amount of evaporation. 
For preserving specimens dry it is only necessary to fix in 
some way the tissues so that the animal will keep its shape, 
and then to dry it, preferably by artificial heat. A few Echino- 
derms do not need this preliminary fixing but may be dried 
at once. 
*The limits of our space will not allow of a full description of the dredge or 
dredging; such may be found in almost any work on seashore animals, such for 
instance as J. H. Emerton’s “Life on the Seashore,” [Salem, Bates.] 
