CORAL-MAKING ACTINOID POLYPS. 41 



body ; but whether the young Actiniae were produced by bud- 

 ding from this part of the body, or whether they had. colonized 

 there after being produced, in the ordinary way, he was un-, 

 able to determine. In all cases the young ultimately sepa- 

 rate from the parent. 



These' polyps have also the faculty of reproducing lost 

 parts ; and to such an extent that a mere fragment, if it be 

 from the lower part and include a portion of the base, will re- 

 produce all the rest of the Actinia, even to the disk, tentacles 

 and stomach. Thus the mere forcible tearing; of an Actinia 

 from the rock to which it is attached may result in starting a 

 crop of new Actiniae. 



Although Actiniae have no internal coral secretions, they 

 sometimes make a thickened epidermic plate at the base, and 

 also in a few cases around a part of the body. This is how- 

 ever not a result simply of an epidermic secretion, but arises 

 from an exudation of mucus from the surface, and the entan- 

 gling thereby of minute particles of foreign or dead matters. 

 A case of the kind, in an Edwardsia where the body is thus 

 encased, is mentioned and explained on page 25, 



The above are the more prominent characters of the Actin- 

 ia tribe of polyps. The special features distinguishing them 

 from the coral-making polyps are the following: (1), They are 

 simple animals, or, if they bud, the buds early separate from 

 the parent ; (2), They have a muscular base ; (3), They are gen- 

 erally capable, more or less perfectly, of locomotion on the base 

 by means of its muscles ; (4), They sometimes possess rudimen- 

 tary eyes ; (5), They have no internal coral secretions. Each 

 of these characters is evidence of the superior grade of this di- 

 vision of Polyps. 



