00 NATURAL HISTORY OF OUR SHORES 



In early spring, attached by a gummy thread to the 

 edge of the burrow, may often be seen little pear-shaped 

 cocoons of a brown colour and gelatinous feel. These 

 are its egg cases, and in these the young hatch and develop 

 until nearly the same form as the parent, when they break 

 away and proceed to burrow. 



This method is not common among marine worms, the 

 young much more frequently commencing life as free- 

 swimming, barrel-shaped ciliated embryos called Trocho- 

 spheres. For example, in the same localities, and also in 

 early spring, may often be seen transparent, green-coloured 

 balls of very tender jelly, each about the size of a goose- 

 berry. These are the egg cases of another worm, usually 

 those of one named Phyllodoce viridis, a small and slender 

 one, with a row of leaflike organs on each side, folding 

 over the back. 



If one of these cocoons can be found which is beginning 

 to be disintegrated, part of it showing white and ragged, 

 it will repay the interested observer to place it in a bottle 

 of clear sea-water and examine with a pocket lens. It 

 will then be seen that the " blob " itself is colourless, and 

 that the green colour is due to the myriads of little trocho- 

 spheres which are now breaking away and swimming 

 actively. A bright scarlet spot is apparent on each one 

 of these lively little organisms. These are the eyes. 



A splendid worm, which usually heads the list in the 

 annelida, is the so-called " Sea-mouse " (Aphrodita aculeata). 

 It is about four inches long by one and a half inches broad, 

 and about an inch in thickness. It is obtusely pointed at 

 each end, less obtusely posteriorly. Its seta3 or bristles 

 are of two kinds, one long and silky, the other short, stout, 

 and sharp, of a black or dark brown colour. The fine ones 

 are of resplendent tints, gleaming with all the hues of the 

 peacock's feather. The back is clothed with overlapping 

 scales, which are again covered with a grey coating of fine 



