322 



C(ELHELMINTHES. 



open. The space between the horseshoe- shaped intestine and the 

 body surface is completely filled by a pa- 

 renchyma containing muscle cells, and 

 correspondingly the excretory organs are 

 proton ephridia. In our fresh-water Urna- 

 tilla gracilis * these organs are branched 

 and begin with flame cells. Pedicellina * 

 and Loxosoma, marine. 



Sub Class II. Ectoprocta. 



In the Ectoprocta there is a spacious, 

 often ciliated, coelom between the alimen- 

 tary canal and skin, so that these are 

 separated and have a certain amount of 

 independence (fig. 295). On this account 



FlO. 294. Loxosoma Rinqulare. -, . ,. j -i -i , -i n 



(After Nitsche.) single in- nas arisen a peculiar method (wholly 



dividual in optical section. :j .c -ri 11 11 \ i i-" 



A, rectum; Ga, ganglion; incleiensiDle morphologically) oi treating 

 8toma e c s hl ne;r ' tentacles; ^them as two individuals, polypid, the in- 

 testine and tentacles; cystid the rest, especially the body wall and 

 skeleton. 



FIG. 295, Flustra membranacea (after Nitsche), a single animal, a, anus; etc, ectocyst: 

 en, entocyst; /, funiculus; 0, ganglion; fc, collar which permits complete retrac- 

 tion; m, stomach, also dermal muscular sac; o, oesophagus. A^ avicularium; //' 

 vibracularium of Bugula. (After Claparede.) 



The cystid is cup-shaped or saccular. It consists of an endo- 

 cyst the body wall and an ectocyst a cuticular skeleton, usually 

 strongly calcified, secreted by the ectoderm. The surface of the 



