THE CEPHALIC TENTACULA. 193 



sembling that so often witnessed with the kitten, or 

 the playful whelp, when either of these animals 

 foolishly imagine that the tip of their tail is adorned 

 with some coveted tit-bit. 



The branchial organs of my specimen were very 

 beautiful objects, being formed of three blood-red 

 spiral tufts, the effect of which were heightened by 

 their being placed in contact with the drab, coloured 

 cephalic* tentacles, which seemed to be almost in- 

 numerable. These latter organs, although apparently 

 so useless when seen closed, are in reality of the 

 greatest importance to the Terebella, for they not 

 only act as auxiliary organs of respiration, and aid 

 most materially in building its dwelling-place, but 

 also constitute the real organs of locomotion. 



' They consist/ says Dr. Williams, ' of hollow 

 flattened, tubular filaments furnished with strong 

 muscular parietes. The band may be rolled longi- 

 tudinally into a cylindrical form, so as to enclose a 

 hollow cylindrical space, if the two edges of the band 

 meet, or a semi- cylindrical space if they only meet 

 imperfectly. This inimitable mechanism enables 

 each filament to take up and firmly grasp at any 

 point of its length a molecule of sand, or, if placed 

 in a linear series, a row of molecules. But so per- 

 fect is the disposition of the muscular fibres at the 

 extreme free end of each filament, that it s is gifted 



Cephalic, belonging to the head. 



13 



