PEDICELLARIZ OF ECHINODERMATA. 179 
and covered by a fleshy, sensitive, musculo-membranous en- 
velope, continuous with the common integument of the animal. 
The pedicellariz of the genera Amphidetus, Spatangus, 
and Kchinus, possess, in addition, a calcareous style or stem, 
which is also covered by a prolongation from the skin or 
gelatinous envelope of the animal, and the basal end of the 
style is enlarged for articulation with a smaller knob or 
elevation upon the shell, adapted to its reception, in a ball- 
and-socket-like movement. 
Few objects are of greater beauty than the pedicellariz of 
the Echinodermata, as the highly reticulated character of the 
structure, the brilliant transparency of the crystalline sub- 
stance, and sparkling, gem-like elegance, fully testify. But all 
these characters may be elicited by ordinary examination in 
the microscope, with transmitted, reflected, or oblique rays 
fallmg upon them. Yet the highly doubly refracting pro- 
perties of carbonate of lime or Iceland spar, of which they 
are composed, make them still more lovely objects when they 
are examined by polarized light and the selenite stage, but 
without the analysing crystal above the eye-piece. Under 
these circumstances the pedicellarize themselves become their 
own analysers, by double refraction; and the transparent, 
colourless valve of pedicellariz becomes either red or green, 
blue or yellow, according to the thickness of the selenite plate 
beneath them. Some Echini, as H. lividus and E. neglectus 
. (Forbes), are well supplied with a deep-blue colouring matter, 
which gives a beautiful tinge to the spines, which is not re- 
moved upon boiling in strong potass lye. The pedicellariz 
under these circumstances also possess the purple tint of the 
spines, the colourmg matter existing in some sort of com- 
bination with the crystalline carbonate of lime. These 
coloured objects remind one of brilliant sapphire gems, pro- 
fusely decorating the wondrously constructed Echinoderm, 
less costly and far more elegantly cut than the far-famed 
jewels of Her Majesty, but destined to be hidden in the dark 
abyss of ocean’s depths until brought to light by the 
researches of the naturalist, and rendered evident by the 
Jenses and mirrors of the microscopist. 
When it is desirable to examine the movements of these 
organs it is advisable to remove a portion of a living animal 
and insert it in a small trough of sea water, and watch the 
pedicellariz with a low-power objective upon the stage of the 
microscope. But when it is only desired to examine the struc- 
ture of the pedicellariz it is better to remove the organ with a 
scissors or small forceps, and, having placed it on a slide with 
a small quantity of glycerine containing a little caustic 
