XVII 



ANATOMY 



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characteristic yellowish pigment. The stomach gives off the 

 intestine (in), which is lined by strong cilia, by means of which 

 a rotatory movement is given to the faeces contained in it. This 



Fig. 234. Alcyonidium albidum Alder, Banyuls-sur-Mer. Diagram showing the struc- 

 ture of a single zooecium with its polypide retracted : a, anus ; d, diaphragm ; e, 

 ectocyst ; em, ectoderm ; f, funiculus ; g, ganglion ; *', intertentacular organ ; in, 

 intestine ; m, mouth ; mm, mesoderm of body-wall ; 0, orifice ; oe, oesophagus ; ov, 

 ovary ; p, parietal muscles ; ph, pharynx ; p.v, parieto- vaginal muscles ; r, rectum ; 

 r.m, retractor muscles (contracted) ; s, stomach ; t, testis ; tn, tentacles ; t.s, ten- 

 tacle-sheath or kamptoderm. (After Prouho. 1 ) 



communicates by a narrow passage with the rectum (V), which 

 opens by means of the anus (a). 



Tn the retracted condition the tentacles (tn) lie in a cavity 



1 Arch. Zool. Exp. 2 ser. x. 1892. 



