NEREIS. 149 
It is the largest of the whole tribe, in as far as I am aware, inhabit- 
ing the Scotish seas. Likewise its characters are so distinct, that it can- 
not be readily mistaken. 
Length two feet ; breadth half an inch. Body composed of above 
400 segments, always multiplying with age. Between the segments are 
three or four interannulations, on the prolongation of which the exten- 
sion of the specimen seems to depend. Each segment consists of a 
transverse central portion, with a broad flattened organ, equally large, 
on each side, from the lower part of which a pencil on the body issues. 
The head is provided with eight definite antennular organs, and some 
of inferior dimensions, terminate the anterior extremity. The posterior 
extremity is terminated by a fork. Two dark blue or black eyes are 
situate on the front of the head ; if there be others, they are very indis- 
tinct. A stout, yellowish proboscis is projected from before. 
The natural colour of this animal is a fine green ; bluish-green on 
the centre of the back, iridescent, reflecting a bright blue, as is also seen 
on the belly. The paddles, as they may be justly denominated, always 
green. Young specimens, likewise, are wholly green, the bluish colour 
and iridescence belonging only to the older. 
I have not been able to ascertain that any sheath or external cover- 
ing is constructed by this Nereis; but a remarkable profusion of clear 
glutinous matter is secreted from the whole body, so great, that it may 
be nearly equal in weight to the specimen itself. 
Probably the natural habitation of all the Nereids is among sand, 
or in the crevices of rocks, where sand is present. 
During the day this species lurks in concealment, especially under 
any large flat shell, where it reposes and unfolds from its many convolu- 
tions at night, apparently in quest of prey. - Perhaps it feeds on the 
smaller living animals, for which the size and action of the proboscis 
seem peculiarly adapted. Sometimes, but very seldom, portions of mus- 
sel have been absorbed ; and once it seemed to me that a large specimen 
had devoured a smaller, which occupied the same vessel, as its disappear- 
ance could not be otherwise accounted for. But all kinds of sustenance 
