174 J. E. Dueeden — Jamaican Actiniaria : 



Genus. — ACTINOPORUS, Duchassaing. 



Actinoporus, Duchassaing, 1850; Duchassaing & Michelotti, 1860. 



Discosornidee, in which a radial tentaculate area, hearing more than one row of 

 tentacles, communicates with each mesenteric chamber. Tentacles all vesicle-like, 

 either simple or lobed, no distinction between a peripheral and an inner series. 

 The column-wall is provided with verrucas distally. Sphincter muscle strong and 

 circumscribed. Mesenteries all complete. A weak ectodermal musculature on the 

 column and stoinodgeum. 



The genus was instituted by Dr. Duchassaing (1850, p. 10) for a single West 

 Indian species of anemone, differing much in regard to its tentacles from any other 

 known form. Later, in collaboration with Michelotti (1860, p. 46), he gives a 

 further description of the genus, in which he evidently regards the tentacular areas 

 as homologous with the frondose areas occurring in Oulactis, the internal cycles of 

 ordinary tentacles, present in the latter, being wanting. 



An acquaintance with these two genera demonstrates, however, that no such 

 relationship can be sustained ; the frondose areas in Oulactis are of columnar origin, 

 and occur outside the sphincter region, while those of Actinoporus are discal, and 

 within the sphincter region. 



The most salient character of the genus is the occurrence of more than one row 

 of tentacles communicating with each endoccale and exoccele, a feature unique 

 among the Actiniaria, unless the same may be said of Actinodendron and of 

 Discosoma ambonensis. Kwietniewski (1898, p. 410) describes the tentacles of 

 the latter as in radial groups, a condition which seems to me, should certainly 

 warrant at least the generic separation of the form from other Discosomse, in 

 which only one radial row communicates with each mesenterial chamber. 



In the tentacular areas of the oral disc one may perhaps see some relation of 

 degree between this genus and Actinodendron. In this latter, as figured and 

 described by Haddon (1898), the forty-eight tentaculate areas, which likewise 

 correspond with both the endocoeles and exocoeles, are prolonged for some distance 

 as non- retractile lobes, and the tentacles on them are small, arise in an irregular 

 manner, and are dendritic or form " conical bossy agglomerations." One may 

 perhaps regard the lobes of Actinodendron as extensions of the sharply denned 

 areas in Actinoporus, and the dendritic tentacles as exaggerations of the vesicular 

 outgrowths in the West Indian genus. 



From an acquaintance with only a single specimen of Actinoporus, it would be 

 premature to regard the possession of only one gonidial groove (monoglyphic), 

 associated with two pairs of directives, as a constant generic character. 



