310 THE OCEAN WORLD. 
Most naturalists have now agreed to place among the Bryoz 08, 
certain species of animalcules which long remained imperfectly kno" 11 
Amongst these are the Flustra, the EseJiara, and other ascidians. 
The Flustra are marine Bryozoa, whose skin in hardening form s ^ 
thin shell of horny or cellular appearance ; their little cells, more 
less horny, are grouped symmetrically, somewhat like the cells 111 
bee-hive. Sometimes they form a crust which covers the alg® 
other submarine bodies ; sometimes they form ribbon-like stems. 
Fig. 123. Flustra foliacea (Lin nans). 
some species the cells are only found on one side ; in others it occupy 
both. Their orifices are extremely small, and defended by sp 111 
quite microscopic (Fig. 123). 9 
Their tentacles are covered with cils, always vibratile, disposed J 
straight line, which in their movements produce the effect wb lC i 
row of animated pearls might be supposed to produce if x ° 
upwards from the base to the summit of the organ. ^ 
The Eschara form leaf-like expansions, the entrance to their CL 
having also their protecting spines. 
