424 THE AQUARIAN NATURALIST. 



the summit of the cell begins to project, announcing 

 the approaching evolution of the polyp. First a very 

 short white cylinder protrudes ; and then the integu- 

 ment of the body, unfolding like the inverted finger 

 of a glove, displays the exterior of the animal crowned 

 by about thirty-five tentacula, so arranged as to form 

 a bell-shaped cup, the margin of which is slightly 

 everted. The form of the whole creature is elegant, 

 light and beautiful ; it rises very leisurely and gradu- 

 ally from the cell ; but its retreat is most precipitate 

 it vanishes in a moment, and thus the cloud, com- 

 posed of multitudes, is dissipated at once. 



The largest, most vigorous and luxuriant speci- 

 mens of this Bryozoon abound at low-water mark, 

 and they generally prefer a muddy shore ; some may 

 be met with higher up upon the beach, but propor- 

 tionally deteriorated as they are remote from the sea. 



Such Polyzoa are, however, of difficult preserva- 

 tion ; constant renewal of the agitated waves seems 

 to be an indispensable lotion; otherwise a thin mouldy 

 film accumulates upon the surface of the Zoophyte, 

 and the polyps drop from their cells. Hence may be 

 inferred the purpose of Nature in assigning the abode 

 of these animals within the flux and reflux of the tide. 



If vigorous specimens of this elegant Zoophyte be 

 procured towards the end of May, or the beginning of 

 June, and deposited in suitable vessels, innumerable 

 active little bodies, resembling Infusorial animal- 

 cules, will soon be discovered swimming rapidly 

 about (PL VII. fig. 8). 



These creatures, the yemmules of the Flustra his- 

 pida, are of a pure white colour, elliptical in shape, 



