THE POLYZOA, OR BRYOZOA 



107 



weeds, and on pretty well every fragment of shell which 

 has not been subject to attrition, will be seen representa- 

 tives of the group. 



Fig. 41 shows a frond of fucus which is encrusted with a 

 growth of one of these forms, a very common one (Mem- 

 branipora membmnacea), and Fig. 42 shows a small portion 

 of the same enlarged. 



There are thin membrane- 

 ous ones, like the above, and 

 there are also massive stony 

 forms, in which the poly- 

 pidom is strongly calcified. 



Nearly every stone among 

 sea-weed and in rocky places 

 will, on being turned over, 

 reveal pink-coloured patches 

 that, on a close examination, 

 show the cellular structure as 

 described. These are named 

 Lichenopora. from their re- 

 semblance to growths of some 

 of our familiar lichens. 



Very abundant are little 

 circular patches about a quar- 

 ter of an inch in diameter, 

 and in which the cells are tubular, radiating from the 

 centre. This is Lichenopora hispida. 



Some form very large masses, with rigid leaflike ramifi- 

 cations, forming as it were a huge honeycombed structure, 

 the millions of little builders occupying the sides of its 

 walls. This form may frequently be seen attached to 

 large shells, or may form masses, eighteen inches or more 

 in area and a foot high, attached to some point on gravelly 

 bottom. This is Lepralia foliacea (Fig. 43). 



From the under side of boulders near low water-level 



Fig. 42. A small portion of 

 Me-inbranipora membranacea, 

 as seen with pocket lens 



