CTENOPHORA ; CYDIPPE. 539 



trance to the short oesophagus, which terminates in the stomach ; 

 it can be closed by the animal when irritated ; but when freely 

 swimming through the water, it is always widely dilated. From 

 the stomach, there passes a narrow straight intestine, which 

 terminates at the opposite extremity of the body. When the 

 animal is in active movement, therefore, a continual stream of 

 fluid will enter its mouth, and will pass out again behind ; and 

 from the minute particles contained in this fluid, its nourishment 

 is probably in part derived. 



1 192. These apparently powerless little animals feed, however, 

 like the Discophora, upon species of much higher organisation 

 and firmer texture ; and they are provided with similar means 

 of obtaining them. From the vicinity of the mouth arise two 

 filaments or tentacula, which are many times its own length. 

 These are provided with lateral filaments, which arise at regular 

 intervals from one side along their whole course, and are spirally 

 coiled like the tendrils of a pea. The principal filaments do not 

 arise from the surface of the body, however, but from the bottom 

 of two deep cavities extending into its interior. Into these 

 cavities the main filaments with their appendages can be entirely 

 retracted. The lateral fibrils seem to contract spirally towards 

 the longitudinal filaments ; and the latter are drawn by irregular 

 contractions into the cavity, so as to be entirely concealed. When 

 the animal wishes to put them forth, it seems to contract the 

 cavity, and the filaments are jerked forth, as it were, not simul- 

 taneously, but first on one side and then on the other. When 

 the main filaments have been ejected from the body, the 

 little tendrils begin to uncoil. When one of these beautiful little 

 animals is placed in a vessel of sea-water, it sometimes remains 

 at the bottom, projecting its long filaments upwards. At other 

 times it darts upwards with great velocity, drawing its long fila- 

 ments after it, retracting and extending them alternately. Not 

 unfrequently it remains for some time at the top of the water ; 

 and, when it wishes to descend, it turns over, drawing up its 

 filaments suddenly, and then swims, mouth downwards, to the 

 bottom of the vessel. The filaments contain a great quantity of 

 thread-cells analogous to those of the other Radiata. They exist 



