42 ON THE COMMON BRITTLE STAR. 
in 13 to 23 fathoms water. “Upon the sponges I seldom fail to 
detect one or more specimens of these minute Star-fish; as many 
as a dozen of various sizes, agreeing in general form, being fre- 
quently clustered upona fragment not more than an inch or so 
long. Ihave thus had abundance of material, and have ob- 
tained them from the small size mentioned above, to the ordinary 
size of this Brittle Star—a regular and progressive increase, 
from the thirtieth of an inch to six or seven inches across. 
From a series of mountings, I have been enabled to trace, step 
by step, the gradual changes in the character and form of the 
spines, plates, and appendages of the animal generally. 
As there are some peculiar circumstances connected with the 
development of these several organs which are not generally 
known, it may not be out of place to put on record such obser- 
vaticns as I have been enabled to make. 
Every one that resorts to the sea-side must be perfectly 
familiar with the common Brittle Star (Ophiocoma resula), and 
doubtless many of onr members have often sought for perfect 
specimens amongst the fishermen’s lines at Cullercoats, and other 
places generally visited during the summer season; and many a 
time they may have been disappointed, on picking up a good 
specimen, to find, while holding it, that it suddenly divests itself 
of its rays; and, as bit by bit breaks up into still smaller frag- 
ments, nothing is finally left but a collection of long sharp spines, 
attached to the ray scales, and the forsaken disc-—projecting from 
which are irregular spokes, in place of the long tapering rays. 
But if, instead of handling, the would-be possessor of a perfect 
specimen provides a vessel of cold fresh water (not sea water), 
and without fingering the specimen, he plunges or drops it 
quickly therein, the fresh water bath will be found to cause so 
violent a shock to the Star-fish as to deprive it of the power of 
throwing off its rays—being completely paralyzed by contact 
with a fluid fatal to marine life—and the experimenter will have 
the satisfaction of obtaining a perfect specimen, which only needs 
careful drying to form a desirable addition to the cabinet. 
Having so obtained a large specimen, let it be carefully ex- 
amined, and the form and arrangement of the rays duly noted, 
