158 NEREIS. 
§ 13. NEREIS PUNCTATA (VILLOSA).—Plate XXI. Figs. 11, 12, 13. 
Length about an inch and a quarter. Body flattened, composed of 
numerous segments, each bordered with a pencil issuing from a sheath of 
remarkable length, together with a very long flexible cirrus rising from 
within the sheath. Two stout tentacular organs are in front of the head, 
and two more slender beside them. Several other organs, apparently 
tentacular, are also present on each side, or in their vicinity. The pos- 
terior extremity terminates in two long hairs. All the villous or hairy 
organs are transparent, rather cartilaginous, very flexible, and somewhat 
moniliform. They are numerous and peculiar. The longer are towards 
the upper portion of the body, where they are seen stretching, contract- 
ing, curving, and turning about in every direction, apparently engaged 
in tentacular offices. They shorten proportionally as they occur farther 
down the body, and therefore their action is less conspicuous. Four 
eyes are set in a quadrangle on the surface of the head. A red blood- 
vessel is visible throughout much of the length.. Colour of the finest spe- 
cimens scarlet ; some are yellowish ; but the colour is much dependent on 
the food. It feeds voraciously on mussel, darting out its proboscis, and 
absorbing a great quantity. The colour changes with the quality of the 
food. 
This animal swims by horizontal undulations. It forms a slight 
silken sheath, and lurks much in concealment. But some individuals 
never indicate any disposition to construct an artificial dwelling. 
Prate XXI. 
Fic. 11. Nereis punctata, 
12. The same, enlarged. 
13. Head, more enlarged. 
