C TENOPHORA. 2 5 I 



tentacles, much longer and coloured red ; it is about the size of a 

 hazel-nut, and phosphorescent. Within the clear substance of the 

 Plmrobrachia, on each side of the stomach, there is a capacious 

 cavity, which communicates with the surface, and within each cavity 

 is fixed the tentacle, of great length, and very slender, which the 



Fig. 103. — Cestum veneris (Lesueur). 



animal can at pleasure shoot out of the orifice and suffer to trail 

 through the water, shortening, lengthening, twisting, twining, or con- 

 tracting it into a tiny ball at will, or withdrawing it into its cavity, 

 short filaments being given off at intervals over the whole length of 

 this attenuated thread-like apparatus, each of which can also be 

 lengthened or shortened, and coiled individually. These proceed 

 only from one side of the thread-like tentacle, although, at a casual 



