216 NATURAL HISTOEY OF 



covered witli an elastic raembrane. The actual orifice 

 for the emission of the animal is at the upper and outer 

 part of this membrane where the integuments are pro- 

 truded by gradual evolution, according to the universal 

 rule in this class of zoophytes, in three successive 

 stages, which resemble, when fully protruded, the slides 

 of a telescope. The first of these is horny, and has a 

 sort of spine in the inner margin ; the second, of about 

 the same length, is of the most delicate filmy trans- 

 parency, and has its margin surrounded by a sort of 

 scalloped frill, composed of short ribs (setae), united 

 by a waved membrane, and diverging at right angles. 

 From this projects the third, which generally bulges 

 more or less at the back or outer side, where the orifice 

 of the rectum is situate. A bell of twelve ciliated 

 tentacles, nearly as long as the interior of the cell, 

 crowns this last evolution." 



There is often a rudimentary cell in front of the 

 raised margin of the zooecium, hence the name chelata. 



Mr. Hincks describes the polypide as remarkable 

 amongst an active tribe for the vivacity of its move- 

 ments. 



The ooecia are borne on imperfect cells, and are not 

 numerous. 



Though occasionally occurring in considerable quan- 

 tities, it is generally found straggling, thread-like, over 

 other zoophytes. 



Genus II. Gemellaeia, Savigny. (Gemellus, double.) 

 Zoaria erect. Zooecia joined back to back. The 

 cells composing the pairs rising one from the top of 

 the other, all the pairs facing one way. Aperture large 

 on the front of the cell, oblique. No Ooecia. — T. H. 



