38 ANTHOZOA HYDROIDA. 



centre, tapered gently upwards, and coated with a very thin 

 faintly wrinkled skin ; while the head is white or faintly 

 coloured, and muricated or roughened with sharp points. 

 Mr. Lister says that it is covered with " short projections 

 like blunt hairs; 1 ' 1 "and it seems," he adds, " to be by their 

 means that the polypi attach with a touch, or release at will, 

 substances that drift within their reach." According to Mr. 

 Hassall, the murications, on the contrary, seem to be " minute 

 cups, similar to those of the cuttle-fish." M. Loven has 

 taken the same view of them. This discrepancy I ascribe 

 to the different manner in which I presume the observations 

 on the organs in question to have been made. Lister's descrip- 

 tion accords well with my own observation when I have 

 viewed the head at freedom ; and the appearance of cups has 

 only been produced when this was compressed between plates 

 of glass. To me the granules or " blunt hairs" appear to be 

 of a glandular nature, secreting a tenacious mucus. When 

 brought in contact with a foreign body, the tentacula in- 

 stantly adhere to it with sensible firmness ; and the act is 

 too instantaneous to be the result of the application of suckers, 

 or of any power dependent on muscular action. But the 

 secreted glue is ever ready to act, and I have more than 

 once seen a film or line of mucus stretched between the 

 foreign object and the head of the tentaculum, when this was 

 naturally withdrawn by the animal itself. 



On a first glance we are apt to imagine that the tentacula 

 could be of little service to the polype ; for, even when they 

 have fixed the errant prey, their shortness must prevent them 

 reaching it to the mouth. This is true, but the difficulty is 

 remedied by the mobility of the head, which can not only be 

 shortened and lengthened at will, but can be turned in any 

 direction, and bent at the same time into a perfect circle, so 

 that its extremity may be applied to whatever tentaculum 

 the prey is adherent to.* 



About the roots of the tentacula there are generally pre- 

 sent some of the reproductive capsules. These are of a round 

 shape and rose colour, consisting of a soft mucous coat or 

 skin enclosing a dark central nucleus. I have found each of 



f " Orificium dilatat, capitulum vibrat, et papillas prolongat abbreviatque ; qui 

 raotus unicus." O. Fabricius. 



