CHAPTER XITi 
POLYZOA 
Phylactolaemata—Plumatella, Cristatella, Lophopus. 
Cyclostomata—Crisia, Hornera. 
Ctenostomata—Paludicella, Alcyonidium. 
Cheilostomata—Bugula, Membranipora, 
Flustra. 
Entoprocta—Loxosoma, Pedicellina. 
Ectoprocta | 
Polyzoa Gymnolaemata 
CHARACTERISTICS.—Small coelomate animals, invariably possess- 
ing the faculty of budding. The colonies nearly always fixed. 
The ectoderm secretes,as a rule, a cuticle, which may be horny 
or calcareous. The intestine is bent in the form of a U, the 
anus and mouth being approximated ; between them is situated 
the nerve ganglion. The mouth is surrounded by a series of 
ciliated tentacles. The individuals of the colonies may be 
hermaphrodite, but the generative cells may ripen at different 
tumes. 
The Polyzoa comprise a very great number of species, which 
can be grouped into two main subdivisions : 
G.) The Eetoprocta, in which the anus lies outside the circlet 
of tentacles which surrounds the mouth. 
(ii.) Zhe Entoprocta, or those forms in which the cirelet of 
tentacles or lophophore embraces both ends of the alimentary canal, 
the anus as well as the mouth. 
The latter subdivision contains very few forms, but the 
former includes a great number of species, mostly marine; a 
few, however, inhabit fresh water. 
Plumatella fungosa is a fairly common representative of the 
freshwater Ectoprocta. It occurs all over Europe, on pieces 
of submerged trees, etc., living by preference in stagnant 
or slowly-flowing water. Each individual of the colony lives 
