336 THE AQUARIAN NATURALIST. 



suddenly reduced in size, and assumes quite a dif- 

 ferent appearance, as if more uniform in structure, 

 and presenting a shagreen surface. A double row of 

 bunches of setae project from the sides of the animal, 

 and thirteen pairs of beautiful vermilion- coloured 

 tufts rise from the back, commencing at about one- 

 third of the length from the anterior extremity ; these 

 last-named organs, which constitute the respiratory 

 apparatus, are extremely elegant, and when examined 

 with a simple magnifying-glass resemble arborescent 

 shrubs, the stems, boughs and branches of which are 

 all in lively action. 



The diversity of colour in this species is very great : 

 of a number collected together, some will be found of 

 a carmine hue, or of a still deeper red, some brownish, 

 and others blackish green, or all these shades are 

 sometimes blended together in the same individual. 



Dwelling constantly in the dark, not only deep in 

 the sand, but generally covered by the sea, the Are- 

 nicola is extremely impatient of light, and when in 

 confinement continually attempts to penetrate down- 

 wards, even when there is no sand in the vessel ; but 

 if amply provided with this material, it soon screens 

 itself from view. 



The Arenicola piscatorum connects the naked with 

 the sedentary Annelida. A viscid secretion exudes 

 from the anterior half of the animal, to which the 

 sand adheres, and hence, when the worm is dug up, 

 this part is generally found to be covered with an 

 imperfect arenaceous tube, within which the move- 

 ments of the worm are performed with perfect free- 

 dom, but which cannot be removed entire, on account 



