Haddon and Shackleton — A Revision of the British Actinice. 



635 



a variety of an older form ; and the name has only been occasionally retained for 

 this variety of that particular species, whilst Epizoanthus has been universally 

 adopted for the more typical forms of this genus. Both names were originated 

 by Gray, and we have therefore less hesitation in keeping to the latter. 



Erdmann examined some free Zoanthete which were dredged by " H. M. S. 

 ' Triton,' 640 Fuss " (1885, p. 481). Without paying any attention to the litera- 

 ture of the subject, he relegated these to a new genus, which he did not name. 

 Very likely it is the Shetland species. Danielssen (1890) described specimens which 

 he referred to Erdmann's new genus, which he named Mardoell ; and he called his 

 new species M. erdmanni (p. 117). Through the courtesy of Dr. Danielssen we 

 have been able to examine this form, and have cut sections of it. We are perfectly 

 satisfied as to its specific distinction from the free variety of E. incrustatus. 



The imperfect mesenteries of E. erdmanni are much more developed than in E. 

 incrustatus ; and there is almost invariably a well-marked lacuna in the mesogloea at 

 the base of the insertion of each mesentery. 



In every respect it is an Epizoanthus, the sphincter being mesoglcBal instead of 

 endodermal, as Danielssen states, and the arrangement of the mesenteries is 

 macrocnemic, though Danielssen's figures do not show this. 



BRITISH SPECIES OF THE GENUS EPIZOANTHUS. 

 E. incrustatus, Diib. & Kor., 1847. E. paguriphilus, Verr., 1882. 



E. couchii, Johnst., 1838. 

 (E. rubricornis, Holdsw., 1861 ) 



E. m.acintoshi, n. sp. 

 E. wi'iglitii, n. sp. 



SYNOPSIS OF BEITISH SPECIES OP EPIZOANTHUS. 



E. paguriphilns. 



Forming carcinsecia, 



Free Colonies, 



One polyp ventral, remainder marginal, 



Polyps on upper surface only, 



Polyps radiating in one plane from a common f E. incrustatus. 

 point ; diameter to heigiit of polyp as 1 to 2, 



Polyps radiating in all directions from a common 

 point ; diameter to height of polyp as 1 to 4, 



(E. mhricornis.) 



'«. Coenenchyme usually band-like \ E. couchii. 



Diameter to height of polyp as 1 to 4, . . . \ (S. W. Ireland.) 

 „ as 1 to 3, ... i (S- W. England. 



Incrusting Colonies, 



Coenenchyme probably band-like ; diameter of 

 polyp nearly as great as height, 



E. macintoshi. 



Ccenenehyme irregular ; diameter of polyp greater \ ^ m^ahtii 

 than height, ' 



The above relative proportions of diameter to height refers solely to contracted 

 spirit specimens. 4X2 



