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



ISATJRTJS, Gray, 1828. 



Large brachycnemic Zoanthese, with a single mesogloeal sphincter muscle. 

 The body- wall is unincrusted ; the ectoderm is discontinuous ; ectodermal and 

 endodermal bays and small canals in the mesogloea. Monoecious or dioecious. 

 Polyps in small clusters or solitary. 



RECOGNIZED SPECIES. 



I. tuberculatus, Gray, 1828. — Guadeloupe, Bermudas, [M.]. 



I. spongiosus (Andres), 1877. — Port Natal, [A.]. 



1. asymmetricus, Hadd. & Shackl., 1891. — Torres Straits, [H. & S.]. 



PROBABLY BELONGING TO THIS GENUS. 

 I. cltftoni (Gray), 1867.— W. Australia. 



[? Mammillifera,* Lesueur, 1817. 



M. auricula, Lesueur, 1817. — St. Vincent; Dominica. 

 M. nt/mpkcea, Lesueur, 1817. — St. Christopher.] 



GEMMARIA, Duchassaing et Michelotti, 1860. 



Solitary brachycnemic, Zoanthese, with a single sphincter mesogloeal muscle. 

 The body-wall is incrusted with particles of sand. The ectoderm is usually 

 discontinuous, but may be continuous. Lacunae and cell-islets are found in the 

 mesogloea. Dioecious. 



• ' RECOGNIZED SPECIES. 



G. rusei, Duch. & Mich., 1860. — St. Thomas, Bermudas, [M.]. 

 G. isolata, M'Murr., 1889. — Bahamas, [M.]. 



G. macmurricki, Hadd. & Shackl., 1891. — Torres Straits, [H. & S.J. 

 G. mutuki, Hadd. & Shackl., 1891. — Torres Straits, [H. & S.]. 



PROBABLY BELONGING TO THIS GENUS. 

 G. philippinensis (Gray), 1867. — Philippines. 



* The position of this genus cannot be settled until the type species have been recovered and 

 sectionized. 



