COELENTERA TA 77 



apparatus possibly serves as a balancing organ, and helps to 

 keep the floating animal the right way up. 



The reproductive organs are arranged along the meridional 

 canals, the male cells on one side and the female cells on the 

 other of each canal. The ova and spermatozoa escape through 

 the canals, and eventually leave the body through the mouth. 



The main features of the anatomy of the Ctenophora have 

 been indicated in order to render intelligible their possible 

 relationship on the one hand to the Anthomedusae and on the 

 other to the Turbellarians. There is a mass of interesting 

 detail with reference to these animals which cannot be referred 

 to here. 



The Anthomedusan Gtenaria has the mouth of its umbrella 

 very much contracted, and the edges have grown round and 

 over the manubrium, which is small. The opening into this 

 sub-umbrella cavity corresponds with the opening into the 

 stomach of the Ctenophor ; and the lumen of the latter, lined as 

 it is with ectoderm, corresponds with the sub-umbrella cavity 

 of Gtenaria. The shape of the medusa is very like that of 

 Cydippe, and its surface is provided with eight rows of modified 

 ectodermal cells, which correspond in position with the 

 eight rows of vibratile plates in Ctenophors. The arrange- 

 ments of the enteric canals also approaches that of Cydippe, 

 and the resemblance between the two animals is further in- 

 creased by the presence in both of two long fringed tentacles 

 which project from pouches as in the Ctenophora. 



The Gestus veneris, or Venus's girdle, is a Ctenophor in which 

 the spherical form has been replaced by a flattened band-like 

 shape. It is found swimming at the surface of warm seas, and 

 moves through the water by a series of graceful undulations. 

 Beroe, in which the stomach attains a very great size, has no 

 tentacles. 



The group is a carnivorous one, the chief food being pelagic 

 organisms. Many of them are phosphorescent. 



