1867.] r)R. J. E. GRVY ON zoanthin.t;. 233 



316. SiPHONARIA ATRA. 



Siphonaria atra, Quoy et Gaim. Voy. de I'Astrol. vol. ii. p. 337, 

 pi. 2;). f. 41, 42. 



Painted inside with broad black stripes. Found also in Japan 

 and the Pacific Islands. Length 1 inch. 



5. Notes on Zoanthina, with the Descriptions of some New 

 Genera. By Dr. J. E. Gray, F.R.S. 



IVI. Milne- Edwards, in his ' Coralliaires ' (vol. i. p. 226), divides 

 the Actinidce into two groups: — one in which the covering of the 

 body remains soft and does not form a polyperoid ; and, secondly, 

 the Zoanthince, in which the integument of the body thickens and is 

 strengthened with sclerotes, so as to form a coriaceous polyperoid. 

 But in the larger character of the family (at p. 298) he adds that 

 they are aggregate polypes, which multiply by basal buds formed of 

 the tegumental tissues ; and he confines the family to the genera 

 Zoanthus and PaJythoa, — the first arising from root-like stolons, 

 and the other from a broad laminal expansion. 



There can be no doubt that the grou}) so defined is very natural ; 

 but there are several genera of Actinince that have considerable re- 

 lation to Zoanthus, not mentioned by Milne-Edwards, which do not 

 come under either of these characters : that is to say, there are some 

 which have the outer skin thick and strengthened with imbedded 

 sand or calcareous particles, which are not aggregate and do not 

 increase by basal buds, arising from neither root-like fibres nor an ex- 

 panded base, but which are free ; on the other hand, there are other 

 genera which do not arise from basal buds, some of which have a 

 thick cartilaginous skin not strengtlieued by sand or calcareous con- 

 cretions, and others which have a thin membranaceous skin. 



x\ll these genera have only a single or double row of very short 

 tentacles, which are placed round the edge of the oral disk far from 

 the mouth, which when the oral disk is contracted are completely 

 hidden. 



I think that these animals should form a family distinct from 

 Aciinidee, which may be called Zoanthidee. 



The zoanthoid polypes, in Lesueur, Dana, and Milne-Edwards's 

 * Coralliaires,' are divided into groups, according to the form of the 

 base from which they arise, — some, as the Zotuithi, having cylindri- 

 cal stolons, and others, as the Palythoa, an expanded foliaceous 

 base ; the latter are again divided according to whether the polypes 

 are entirely or partially separate, or confluent nearly to the mouth 

 of the cells, — all, no doubt, very good characters for the separation 

 of the species into groups. 



They separate themselves into two very natural groups, according 

 to the structure of the external surfaces of the polypes. 



In many, which may be called Zoanthi malacodermi, or soft- 



