286 THE AQUARIAN NATURALIST. 



which turn a little inwards. The outside of these 

 singularly beautiful arms is smooth, and of a purple 

 colour, darkest at the tips of the rays; the inside is 

 most elegantly ciliated with two rows of fimbrise 

 along each ray, of a chestnut colour, shaded to a 

 purple near the centre (PL V. fig. 9) . 



This animal is capable of the most sudden con- 

 traction, from eight or ten inches in length to three 

 or four. It has between a hundred and fifty and a 

 hundred and sixty joints, gradually tapering towards 

 the posterior extremity. 



The case or tube wherein the animal lives is wholly 

 gelatinous, of a very firm and elastic nature, greenish 

 on the outside, but usually stained black by the soil 

 the creature inhabits. These cases are composed of 

 many layers or strata, and when the first coat is 

 removed the remaining part is quite transparent, and 

 the animal nearly as distinctly seen as through glass. 

 This elegant worm is occasionally met with unco- 

 vered at the lowest ebb of spring tides. The case is 

 buried beneath the surface of the beach, and is only 

 discoverable by a small portion which projects above, 

 appearing like a piece of black jelly. When the tide 

 returns, it displays its beautiful tentacula, but rarely 

 exposes its body. 



In its native abode it recedes on the slightest 

 alarm ; and when the gelatinous case is taken in the 

 hand, and the animal is extended within it, the sudden 

 contraction within the tremulous tube produces a 

 singular and instantaneous vibratory shock, that, be- 

 ing unexpected, is rather startling, and might make a 

 timid collector drop so valuable a prize. 



