THE MOSS ANIMALS AND CORALLINES 
Polyzoa or Bryozoa. 
MOMENT’S glance at a bit of seaweed or the most casual in- 
+ spection of the rocks below low tide level, will reveal the fact 
they are often covered with delicate lace-like growths, or with more 
or less highly colored incrustations, or small tree-like forms. 
These are the moss animals or corallines. They live in col- 
onies, and grow by budding, the entire colony having grown 
from a single individual, and thus while the individual creatures 
are themselves of microscopic size, the colony being composed of 
hundreds or thousands may spread over a considerable area or con- 
stitute a small tree-like, or moss-like, growth. 
Each little animal of the colony occupies a separate stony or 
horny capsule into which it may withdraw and even close the 
opening with a lid, the aperture being still further protected by 
spines around its edge. 
The mouth is surrounded by tentacles that in many species 
arise from a horseshoe-shaped or disk-like base. These tentacles 
are always beset with hair-like bristles which by their movements 
serve to set up currents, and thus to drive minute organisms into 
the mouth, 
The intestine is U-shaped and bends back so as to open on the 
dorsal side near the mouth, while the principal nerve centre is situ- 
ated between the mouth and the vent. In some of the forms there 
is a single pair of kidney organs, the ducts of which open near the 
mouth. 
We see, therefore, that although these creatures often bear a 
close superficial resemblance to hydroids they can at once be dis- 
tinguished by their bristled tentacles and complete alimentary tract. 
Indeed a careful study of their development and anatomy has shown 
that they are closely related to the brachiopods and worms, and that 
their present forms have been brought about by ages of sedentary 
life. Being stationary they have had little need for sense organs, 
