BE-CLASSIPICATION OF MiJLLEBIA AND HOLOTHURIA. 163 



PROPOSED RE-CLASSIFICATION OF THE GENERA 

 MULLERIA AND HOLOTHURIA. 



By Joseph Pearson. 



(With one Plate.) 



THE suggestions embodied in the present paper are the 

 result of a careful examination of a large number of 

 species of the genera Mulleria and Holothuria. These two 

 genera are separated from each other by a single character, 

 namely^ the presence of anal teeth in the former and the 

 absence of these structures in the latter. The only point in 

 favour of this basis of classification is that it is convenient 

 and simple. But taxonomic distinctions must necessarily 

 be made in accordance with relationship, and there is good 

 reason for believing that the accepted classification based 

 upon the presence or absence of anal teeth gives no true 

 conception of the affinities of this group. For example, the 

 relationship between Mulleria miliaris and Holothuria mar- 

 morata is much closer than that between the latter species 

 and Holothuria impatiens or than that between Mulleria 

 miliaris and Mulleria maculata. 



The affinities of the various species of the group are rendered 

 much clearer by a systematic examination of the calcareous 

 ring. This structure has never before received the attention 

 it undoubtedly deserves, and one finds it dismissed with such 

 statements as " typically Aspidochirote " or " without poste- 

 rior prolongations." As a result of such a careful compara- 

 tive study not only of the calcareous ring, but also of the 

 other organs of the body, I have been impressed with the 

 need for a more scientific classification than the one at pre- 

 sent in vogue. 



I propose to unite the genera Mnlleria and Holothuria under 

 the latter name, and to divide the genus into five sub-genera. 



