158 NEREIS. 



13. NEREIS PUNCTATA (VILLOSA). Plate XXI. Figs. 11, 12, 13. 



Length about aa 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. Ah 1 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. 



PLATE XXI. 



FIG. 11. Nereis pwnctata. 



12. The same, enlarged. 



13. Head, more enlarged. 



