54 VERMES. 
which are obviously hispid, or bearing external organisation ; and, 3. The 
segmentive or Annelide kinds, much is still wanting. It is not clear 
where one genus terminates, and another begins, or where, in nume- 
rous instances, the subject has the precise characters of integrity or 
mutilation. 
It is self-evident that the great embarrassment to forming a suitable 
and permanent arrangement of worms, orginates from the mutability of 
form, and the absence of external organs. The latter are most import- 
ant features, whether from shape or position. And as neither the site of 
the mouth can be discovered in many during life, nor have they visible 
eyes, what effectual substitutes shall be chosen by the naturalist ? 
Worms are smooth, soft animals, inhabiting the sea, fresh-waters, 
the flesh or intestines of living creatures, and elsewhere, susceptible of 
various form by extension, contraction, or inflation,—all under extraor- 
dinary modifications. 
By a peculiar provision of Nature, a copious secretion lubricates the 
body, apparently designed as a preservation from abrasion by the harder 
substances amidst which they dwell, and to facilitate their motion 
amongst them. Perhaps it is present im all. ; 
This substance, which belongs to the hispid as well as the smooth, 
to the Annelides alike with the simple worms, is produced of very un- 
equal quantity and quality. Sometimes it is abundant, ropy, and trans- 
parent, and secreted from the whole surface, from certain parts of it, or 
partially from organs for peculiar portions only. In some it is consoli- 
dated as a silken sheath, wherein the tenant has a permanent dwelling ; 
in others it is the lining of a covering framed of indurated materials, and 
mixed up with other elements, such as mud, sand, or stones. It is 
an ingredient in the paste, compounded by a few for their protection, 
and it is bountifully provided as a testaceous dwelling for the Serpulx, 
and others of the vermicular tribes. 
The real distinction, position, and faculties of the organs secreting 
a viscid matter for the lower animals, and the solid, hard, resisting shell 
of those considered far above them, is yet but insufficiently understood. 
But it is produced in such a manner as to be only an addition to what 
