252 THE MEDALS OF CREATION. Cuap. VII, 
important character of having originated, (with but few ex- 
ceptions,) from aggregations of those minute beings termed 
PotypEs (many-feet*). The common Hydra (Wond. p. 600), 
or fresh-water polype, that inhabits pools and streams, is a 
familiar example of a free animal of this kind, consisting of 
a cellular gelatinous substance, in the form of a short tube, 
or pouch, surrounded at the upper margin by long tentacula, 
or feelers, which appear to the naked eye as delicate threads. 
The Polypifera, properly so called, are groups of polypes, 
permanently united by a common integument or axis, each 
animalcule having an independent existence. A common 
support or endo-skeleton, termed polyparium,t is secreted 
by the integuments, which varies in its nature from a mere 
gelatir.ous, or horny material, to an earthy, calcareous, and 
even siliceous substance, that remains when the polypes die, 
and their soft parts have perished. All the varieties of 
corals, &c. are nothing more than the durable structures of 
ageregated masses of such beings. 
It may here be necessary to notice a prevailing error, 
regarding the mode in which the substance called coral is 
produced. It is very generally supposed that Corals, par- 
ticularly those bearing stars and cells, have been constructed 
by animalcules, in the same manner as is the honey-comb, 
by the Bee; and the expressions often employed by natu- 
ralists, of “the coral animalcules building up their rocky 
habitations,” and “ constructing their cells,” have contributed - 
* Aname derived from the tentacula, or processes, which in some 
species serve for prehension, and in others for respiration. 
+ The basis, framework, or endo-skeleton, of these groups of animal- 
cules is termed the polypariwm, or polypidom (polype-habitation) ; 
those of a stony hardness are familiarly known as corals ; these 
names, therefore, refer to the durable substance, and not to the 
animals themselves ; but in familiar writing, the term Coral is often 
used to designate the entire living mass. The Red-Coral forms a 
distinct genus called Corallium. In fossils, the polypariwm alone 
remains, except in very rare instances. 
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