Objects for the Microscope. 169 



SERTULARIA POLYZONIAS. 



You see here that the Polype cells are not opposite each 

 other, but alternate and far apart. There are two varieties 

 of this Zoophyte, the one upright, the other spreading 

 and branching ; it is found on shells and sea-weed, especially 

 on branches of Halidrys. 



These little creatures are very phosphorescent in the 

 dark; if we shake or strike the sea-weed upon which it 

 rests, a shower of diamond sparks seem to be scattered over 

 the frond ; each cell on the delicate spray is a fairy lamp, a 

 moment seen and gone, or sometimes shining on with a 

 faint, gentle light, showing where the little Zoophyte is 

 dwelling. Often when, having gathered a quantity of Ser- 

 tularia pumila during the day, I have handled it at night, 

 the flashing out of a thousand tiny stars has astonished me. 

 What must it be if the tossing wave shakes glory thus from 

 the dark weed in the stormy night, and the ocean depths 

 are illuminated by their living lamps ? 



SERTULARIA OPERCULATA, 



or Sea-hair Coralline, shows the sharp tooth-like cells 

 peculiar to this species, and the vesicles with a rounded 

 operculum on the top. This zoophyte is abundant on the 

 coast, often thrown up on the beach in tufts as much as 

 six or eight inches long, especially after a storm. 



SERTULARIA ROSACEA, 



called the Lily or Pomegranate Coralline, will give you a 

 good specimen of varieties in species, and show you what to 

 observe ; for the cells are not so unlike those of the common 

 Sertularia pumila (the upper part of the cells bent out- 

 wards and downwards slightly), but the vesicles are most 

 unlike. You see they are pear-shaped, wrinkled, cleft at 

 the top, and more silvery in hue. This coralline grows on 

 shells in deep water, and is parasitic on other zoophytes, 

 small white clusters being often found on Plumulariafalcata 

 and Sertularia argentea. 



LAOMEDEA GENICULATA, 



the Knotted-thread Coralline a very common and beau- 



11 



