NEREIS. 151 
parts perished from accidental vitiation of the water, while the head 
was yet wanting. 
If this important part of the animal's organization is reproduced, as 
may be possible, the process advances tardily. .On the 8th of April, I 
procured a large specimen, which had ruptured into three portions. Only 
one of them survived, which extended about two inches ; together with 
another, which might have been originally about ten inches above the 
posterior extremity. This latter portion continued very impatient of the 
light, which abated in a fortnight, but no indications of a regenerated 
head appeared. The wounds in such cases generally heal, and the por- 
tions exhibit much motion, although they do not survive long enough for 
reproduction, if this can actually take place. 
It is otherwise with the lower part, for there seems no doubt that 
the mutilated extremity is extended by regeneration, as appears from the 
example lately given, of fifty segments having been reproduced. 
A beautiful small and active Nereis, about three inches long, of a 
fine green colour, is not uncommon among the crevices of rocks, within 
flow of the tide. To the eye, it seems distinguished by three regular 
rows of specks down the back, which is illusive, for a lens shews them 
to be merely the centre of the segment, and the paddle on each side, all 
exactly resembling the parts of the preceding animals. I have been 
thence induced to identify it as the young ; if otherwise, it bears a very 
near analogy. <A slight tubular covering, hardly to be called a sheath, 
is formed by it of silk and sand. 
A month subsequent to the capture of several specimens of these ani- 
mals, the largest being nearly three inches long, a green globular mass, above 
five lines in diameter, appeared floating in their vessels. It was attached 
slightly to a very thin silken tube, formed on the side of the vessel near 
the surface of the water, having probably issued from one of the animals, 
which kept always in the vicinity. This globular mass consisted of hun- 
dreds of green specks amidst a transparent jelly. Next day, May 25, 
when delineated, its figure had been somewhat impaired, as happens 
frequently with clusters of the spawn of animals. Under the microscope, 
the ova in the mass proved nearly spherical, and quite green ; and on 
