156 PRACTICAL MICROSCOPY. 



scattered marginal spines ; when rubbed betwixt the fingers 

 it exhales an odour resembling oil of lemon. An illus- 

 tration of this common object of the sea-shore is given at 



FIG. 142. 



Fig. 143, while in the next figure (144) is shown a portion, 

 much enlarged. 



When collected, they must be preserved in bottles or 



