150 NEREIS. 
are almost invariably refused ; and the animals become lank and ema- 
ciated from protracted abstinence. 
The mechanism of this creature, its parts, and their powers, are to 
be ranked' among the more conspicuous and admirable works of the 
creation ; nor can they be contemplated without wonder. Issuing forth 
from its retreat, it swims by an undulating serpentine motion in the 
water. Its unwieldy body, gradually withdrawn from its retreat, has its 
multiplied organs unfolded in regular order and arrangement ; so that, 
whether intertwined or free, neither are disturbed by intricacy or confu- 
sion ; each performs its own proper functions, and the general effect by 
the united exercise of the whole. When inactive, the lateral parts of the 
segments generally close over the back ; in activity, they open widely, as 
if so many oars to aid the animal's course, by their successive impulse on 
the water. 
In confinement, these Nereids can be seldom preserved long entire, 
if of large dimensions. The body, unmanageable without ample scope, 
from its length, and the particular structure of so many subordinate parts, 
expose them to frequent entanglement, without time for evolution leisure- 
ly, whence inevitable rupture ensues. An overgrown specimen, whether 
in the natural or artificial state, is therefore comparatively rare. 
A specimen, about twenty-two inches long, was mutilated of part of 
the lower extremity when procured in October. Regeneration followed 
in eleven days ; the last articulations exhibiting a diminutive fork at 
the natural extremity. But on January 22, the body ruptured asunder 
near the middle. Within three weeks the wound at its extremity healed ; 
and against the first days of April, above fifty segments with their pad- 
dles had regenerated, the whole new portion being of a pale green colour. 
But the breadth of this new portion did not exceed a third of that part 
of the body still remaining entire. I speak of the upper half of the 
Nereis as doing so. In regard to the under half, it had lost a small frag- 
ment above, leaving the place ragged, which I endeavoured to correct 
by separating a portion with sharp scissors, in hopes of preservation. 
Accordingly the wound healed in eleven days, but in fifty nothing indi- 
cated regeneration of the defective head, and about a month later, both 
