THE BRYOZOA. 175 
a number of false polypiers, whose animalcules for a long time 
remained but very imperfectly known; such, for example, are the 
Flustra and the Eschara. 
The Flustra (Plate 1X.) occupy cells more or less horny, which 
are grouped symmetrically together, something after the fashion 
of the cells in a bee-hive. Sometimes they form a crust which 
covers the alge and other submarine existences, and sometimes 
they themselves form thin leaves and ribbon-stems. 
In certain species the cells are only found on one side; in other 
species they appear on both sides. The orifice of the cell is 
extremely minute, and is defended by microscopic spines. Their 
A LEAF-LIKE FLUSTRA. 
(Flustra foliacea.) 
tentacles are covered with cils always vibratile, and arranged in 
straight lines. Their movements produce the appearance of a 
row of animated pearls in continual motion, rolling from the base 
to the point of the tentacle. 
The Eschara form leaf-like expansions. The entrance to their 
cells is likewise defended by spines; and, like the flustra, they 
bear a resemblance to a bee-hive, the citizens of which enjoy, at 
the same time, a common and an independent existence. As in 
the polypiers, so is it here—each member of the community 
eats for the benefit of the common establishment, and also for its 
own immediate well-being ; what affects the individual affects the 
colony. ~ 
