36 



THE AQUARIUM. 



Fig. 17. 

 Zygnoeina. 



Fig. 18. 



Oscillatoria. 



the fluviatile arachnidae, and the larger molkiscs ; the latter 

 in browsing through the vegetation on the glass are apt 

 to destroy perhaps a favourite group of stentors." 



Among the plants introduced in this manner will 



probably be included 

 several species of the 

 filamentous algae, such 

 as Zygnaema, and Os- 

 cillatoria of which il- 

 lustrations are given. 



We may be fortun- 

 ate enough to get a 

 few specimens of the 

 lovely Volvox, but it 

 will be difficult to 

 preserve them in our tank for any length of time 

 Whilst we have it though, we may enjoy a good exam- 

 ination of it. It continually revolves by the aid of the 



cilia with which its 

 surface is studded, 

 and within the young 

 volvoces may be seen 

 to revolve similarly. 

 They are frequently 

 to be found in ponds, 

 often in very great 

 profusion. Other lo- 

 comotive plants you 

 are sure to obtain are 

 the Euglenae, — little bright-green bodies with a bright 

 red spot like a gleaming eye at one end of it. But it is- 

 perhaps among the Desmids and Diatoms that we shall 

 find the most beautiful forms of microscopic plant-life. 



Fig. 19. 



Volvox. 



