ITS STRUCTURE. 297 



The genus is distinguished from Laomedea by the 

 cells being placed on long ringed footstalks, wliich 

 spring in an irregular crowded manner from a 

 creeping adherent stem. The stem in this instance 

 had twined about the slender fronds of a small 

 sea-weed. 



The cells in this species are shaped like an old- 

 fashioned ale-glass, being long and narrow, with a 

 slight constriction just above the point of their con- 

 nexion with the footstalk ; and at this constriction, a 

 sort of false bottom, or diaphragm, runs across, which 

 is perforated with a narrow hole in the centre. (See 

 Plate XVIII, fig. 1). The margin is cut into about 

 eleven deep equal teeth, and expands in a very slight 

 degree (fig. 2). The stalk has usually about six or 

 eight well marked rings at each extremity, the middle 

 portion being smooth. The walls, both of the stalk 

 and cell, are thin, and perfectly transparent and colour- 

 less ; the former is permeated, but not filled, with the 

 medullary core, through which a fluid circulates, 

 carrying minute granules wdth a quivering jerking mo- 

 tion. This core is exceedingly attenuated to pass 

 through the perforated diaphragm of the cell, after 

 which it merges into the body of the polype. 



The polype (fig. 1.) is slender (when protruded); 

 dilated at the base into a sort of foot which spreads 

 over the diaphragm, and widening still more at the 

 top, where it fills the mouth of the cell, and gives 

 origin to about twenty (less or more) slender tenta- 

 cles, roughened with whorls of tubercles, and set in 

 two or three series. In the central space surrounded 

 by the tentacles, a large fleshy mouth protrudes, 



