250 PHYLUM ANNELIDA. 
‘ 
(a) Tentacles in a crescent—Fresh water, Crdstatella, Lophopus, etc. 
(6) Tentacles in a circle—Marine, except Pa/udicella ; Flustra, the 
common sea-mat ; Membranzgora, encrusting seaweed, etc. ; Ced/epora, 
very calcareous; Alcyonzdium, gelatinous. 
The Entoprocta include the colonial Pedicellina, with « few allied 
genera, also the non-colonial ZLoxosoma, in which the buds separate 
as soon as they are formed. All the forms are stalked and minute. 
The anus is included within the tentacular circle. In the meta- 
Fic, 129.—Diagram of an Ectoproctous Polyzoon 
(Plumatella), 
Z., Lophophore; P//., pharynx; A., anus; S., stomach; 
M., retractor muscle ; /., funiculus, a cord of mesodermic 
tissue; O., cells that form ‘‘statoblast” buds; B., an 
ordinary bud; Z., epistome over the mouth; 7., tent- 
acles; S%., outer wall of zocecium. 
morphosis of Pedicediina there is an elongation of the dorsal region of 
the body, and a consequent approximation of the mouth and anus on 
the shortened ventral surface. There is no apparent body cavity in the 
adult, and the mesoderm arises from two primitive mesoblasts. The 
nephridia are anterior, minute, and do not serve as genital ducts, but 
resemble the ‘‘head kidneys” of Annelid trochospheres. They are said 
to terminate in flame-cells like those of Platyhelminths. In all these 
three respects the Entoprocta differ from the Ectoprocta, and from the 
Molluscoidea generally. 
