116 THE MADREPORE. 



nor the marginal haze that generally indicates their 

 presence ; still I am as certain of their existence by 

 the results, as if I had seen them. They must evi- 

 dently be very minute ; none but the smallest atoms 

 obeyed the current ; larger ones continued their course 

 or remained motionless. 



Under this power the globular head of the tentacle 

 is seen to be clothed with a dense coat of very short 

 hairs : the warts also of the body are rough, though 

 not so definitely. The tubular nature of the tentacles 

 was singularly illustrated in one instance. Within 

 one of the tentacles was a small living animal, formed 

 like an Annelide, but the imperfect transparency would 

 not permit me to make out its characters with preci- 

 sion : it swam vigorously, with a serpentine wriggling, 

 and was forcibly driven, over and over, towards the 

 narrow extremity of the cavity. I am almost sure, 

 however, that more than its own spontaneous motion 

 was in exercise : it seemed to be driven forward against 

 its strenuous efforts, sometimes making a little way, 

 then hurled along backward. If this was so, the 

 inference is unavoidable, that there is a current over 

 the interior surface of the tentacle as well as over the 

 exterior, and in the same direction. I did not see, 

 however, any evidence of a stream passing through 

 the tip of the tentacle, and hence suppose that 

 the internal waves spend themselves at the extre- 

 mity of the cavity. A curious inquiry remains, — 

 How did the little animal find its way into its living 

 prison ? 



The tentacles are adhesive, but in a slighter degree 

 than those of an Actinia of the same size : I did not 



