LUMBRICUS. 153 
features, accompanied by delineations. It is probable that some of them 
may be withdrawn, on farther examination, for the purpose of being 
placed in more suitable positions. 
Segments, and hairs or bristles, are assumed as the most prominent 
features commonly distinguishing individuals of the genus. 
In some, however, neither of these characters predominate over 
others, their presence being somewhat equivocal. Nor shall I rigidly re- 
ject what most naturalists have to accept as species. 
§ 1. Lumpricus crrratus—Zhe Medusa Worm.—CirratuLvs BOREALIS, 
Lamarck.*—Plate XVIII. Figs. 1, 2, 3, 4. 
Length four inches, greatest thickness three sixteenths of an inch ; 
body composed of numerous segments, and tapering towards each extremity. 
Numerous long and flexible cirri invest the whole body, apparently some- 
what cartilagious, and consisting of an infinite number of rings. These 
cirri originate from every second segment, no one being free of them. 
Two rows run down the back, and continue nearly to the posterior ex- 
tremity. All are longest towards the anterior extremity, shortening as 
they descend. Many are necessarily omitted in the figure, Plate XVIII. 
fig. 1, which would be otherwise confused and indistinct. A section of 
one is represented as enlarged, fig. 2. A pencil of bristles, very difficult 
to be observed, is placed on each side of each segment, sometimes appear- 
ing as if only two of unequal length. But the incessant motion of the 
animal, and their position, rendered the part of difficult determination by 
the microscope. When the animal crawls, the cirri lie above each other 
along the back, presenting a very singular aspect. The mouth is in the 
anterior extremity, and the sustenance of the animal is probably derived 
from mud. 
* Lamarck places this animal among the Annelides, but he thinks it does not belong 
to the genus Lumbricus. Other authorities endeavour to constitute a different place for its 
reception. The work of Andowin and M. Edwards.—L’ Histoire Naturelle du Littoral de 
la France, tom. ii. p. 271, Pl. VII. may be profitably consulted. 
