534 CYLINDRCECIID^. 



Family TI. — Cylindrceciidse. 



VESicuLAniAD.E (part.), Busk, Quart. Journ. Micr. Se. : Alder : Hincks. 

 Vesicularie.e (part.), Smitt, Krit. Forteckn. 



ZocEciA not contracted helow, closely united to the stem at 

 the base, not deciduous ; destitute of a membranous 

 area. 



In this family the zooecium is not an isolated chamber 

 contracted below and only communicating with the com- 

 mon stem through a small orifice at the base, as amongst 

 the Vesiculariidcs, but is closely and permanently united 

 to the stem and preserves its cylindrical form pretty 

 uniformly to the point of junction with it. In some 

 species it rises from an expansion in the course of the 

 creeping stolon, with which its walls are continuous, and 

 which must be regarded as a decumbent portion of the 

 cell itself. During retraction the polypide is sometimes 

 partially Avithdrawn into it. This expansion of the stem, 

 now constituting the basal portion of the zooecium, may 

 be compared with the similar structures in Aetea and 

 Eucratea, and must probably be regarded as represeating 

 the primitiA^e condition of the cell. 



Throughout the family the ectocyst, or wall of the 

 zooscium, is more or less charged with earthy particles, 

 which render it opaque. 



