Haddon and Shackleton — A Revision of the British Actinice. 627 



Sub-family. Macrocnemin^, n. s.-f.* 



Zoanthese in which the sulcar element of the primitive sulco-lateral pair of 

 mesenteries (cnemes) is perfect : — 



GENERA AND TYPE SPECIES. 



Epizoanthus, Gray. Type E. incrustatus (Diib. and Kor.). 



Parazoanthus, n. g. ,, P. axinellce (Schmidt). 



The Zoanthese constitute a very well-marked division of the Actiniae ; no 

 connecting forms between these and any other group are known. 



The classification of the Zoantheee proposed by Erdmann has been adopted by all 

 subsequent writers ; and as his was the first which was based on internal anatomy, 

 we need not enter into a discussion of the earlier systems. 



Erdmann adopts Andres' two families, the Zoanthidse and the Sphenopidse, with 

 the following definitions : — " Zoanthidse : Zoantheen, welche durch ein Coenenchym 

 zu Colonien vereinigt werden ; " and "Sphenopidse: Einzellebende Zoantheen, 

 welche mit ihren abgerundeten Korperende im Sande stecken oder mit einer Art 

 Haftscheibe am Boden festsitzen." It is strange that these families should be 

 based solely upon the habit of growth. In the second family he places Sphenopus 

 and his " genus novum " ; the latter is undoubtedly the free (or Sidisia) variety of 

 an Epizoanthus. It is very probable that this is really the free- variety of the type 

 species of Epizoanthus {E, incrustatus). As this form passes out of the family we 

 see no reason for retaining a family for Sphenopus, especially as an isolated mode 

 of growth occurs in the other family, as M^Murrich has shown that Gemmaria nisei 

 is "solitary, being attached to pebbles without the development of any coenenchy me" 

 (1889, p. 124), and the individuals of his G. isolata " were scattered and buried up to 

 the tentacles in the sand " (1889 a, p. 65) ; and it is characteristic of the genus 

 Isaurus for the polyps to be either solitary, or in small groups with a feeble 

 coenenchyme. We therefore think it preferable to base divisional characters on 

 anatomical differences. 



M'Murrich has adopted Andres' three divisions, the third being the Bergidse. 

 As nothing is known about the structure of the latter we think it better to omit 

 them altogether. 



success. The objection to the word " cneme " is that it has reference to the appearance of a transverse 

 section of an Actinian rather than to a mesentery as it actually exists. As the investigation of the 

 Zoantheee, at least, must principally he made hy means of transverse sections, this objection has not much 

 weight. 

 * Hid. 



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