P. H. GOSSE, _del._ LEIGHTON, BROS.
PEARLY NEREIS. RAINBOW LEAF-WORM.
]
The colours are very beautiful. The leaf-like fins of the sides,
which are somewhat heart-shaped, are of a yellowish green hue,
occasionally clouded with blackish; the middle portion of the back,
which is exposed, is of a rich brown, but flushed with the most glowing
iridescence of blue and purple; while the whole under parts are of a
pearly flesh-colour. As it crawls over the stones, it throws its body
into the most elegant lateral curves, while its suppleness and great
length cause it to cling close to the rock; and thus its outline takes
the form of every projection and depression over which it is wandering.
When disturbed, and often without any apparent provocation, we see the
under side of the tiny head rise from the ground, swell out, and turn
itself inside out, as you turn a stocking, until a great pear-shaped
bag is protruded, fully eight times as long, and thrice as broad as
the entire head. Its whole surface is rough and papillose, and around
its extremity, which is the largest part, there is a row of small knobs
or warts. This curious organ is found under similar conditions in
very many Annelids; it is commonly called the proboscis, or evertile
œsophagus; but in truth it is a special and peculiar apparatus, with
little analogy with anything found in higher animals: it is in some
species furnished with strong horny teeth, and is doubtless employed
for the capture of living prey, and the conveyance of it to the stomach.
The tail of the specimen I refer to was evidently being renewed after
having been accidentally lost. For the body-segments ended abruptly,
and were followed by a portion, not more than an eighth of an inch
long, white, and excessively delicate; but which, when examined with a
powerful magnifier, displayed a division into segments, each segment
carrying its proper cirri; I could count twenty segments within that
minute space, the last of which carried the usual pair of stylets.