BRYOZOANS 



Fig. io6. — Plnmatella polymorpha: i, colony; 2, 

 statoblast. 



darkness. This is the commonest genus of bryozoans, some- 

 times so abundant in waterways that it has to be removed 

 with shovels. 



Occurrence. — Widely distributed as far west as Montana. 

 July-August. 



b, Colony massive, secreting a gelatinous base. 



Family Cristatellidce 



Colonies in compact groups in large spherical masses or flat 

 and rug-like. 



Pectinatella. — The colonies are made up of animals clus- 

 tered on the surface of large masses of jelly which adhere to the 



Fig. 107. — Pectinatella r^iagnifica: i, colony; 2, 

 statoblast. 



137 



