ACTINIANS FROM THE BAHAMA ISLANDS 107 



the genus Ragactis, which he established for a species, R. pulchra, 

 discovered by him in the Mediterranean. The distinction between 

 Ragactis and Heteractis concerns practically the tentacles only, the 

 evaginations upon these structures being in the former genus small 

 and appearing as tubercles, while in the latter they involve the entire 

 circumference of the tentacle, which thus becomes moniliform. How 

 far this distinction is valid can only be determined by further examina- 

 tion of the anatomy of the various species assigned to the two genera, 

 and for the present it seems to me more convenient to retain for the 

 species under discussion the name proposed by its sponsors. 



An interesting fact which has developed from the examination of 

 H. lucida is that it is unquestionably a Sagartid. The occurrence of 

 acontia (to which my attention was first called by Dr. Northrop) and 

 of cinclides, the existence of only six perfect mesenteries and the meso- 

 gloeal sphincter point indubitably to this relationship, and it will be 

 interesting to know whether Ragactis pulchra and the other species 

 assigned to the genus Heteractis are likewise Sagartids. Andres has 

 grouped together in the family Heteractidas several genera, e.g. in 

 addition to the two already mentioned, Eloactis, Rhopalactis, and 

 Stauractis. Of these, as I have already suggested ('93), the genus 

 Eloactis, as judged by the species E. Mazeli, is probably with greater 

 propriety referable to the family Halcampidce, and I have now shown 

 that one at least of the members of the genus Ragactis must also be 

 transferred to another family. Families based upon mere external 

 characters have no firm foundation, tentacles may vary enormously 

 in shape, warts or tubercles may be absent or present within the limits 

 of the same family, and cases like the present show, if proof be still 

 wanting, that the criteria for a proper classification of the Actiniaria 

 are to be obtained only by the careful study of the internal anatomy of 

 the various forms. 



We must add then, provisionally, to the genera included in the 

 family Sagartidae, the genus Heteractis, since one of the forms assigned 

 to it has proved to be a typical Sagartid. Whether, however, the type 

 species of the genus, H. aurora, will also prove to be a Sagartid, or 

 whether it will be necessary to remove H. lucida from the genus Heter- 

 actis, remains to be determined. And furthermore the affinities of 

 Ragactis pulchra must also be accurately studied before the proper 

 generic term for H. lucida can be finally determined. 



