174 J. K. DuerpEn—Jamaiean Actiniaria : 
Genus.—ACTINOPORUS, Duchassaing. 
Actinoporus, Duchassaing, 1850; Duchassaing & Michelotti, 1860. 
Discosomidee, in which a radial tentaculate area, bearing 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 verruce distally. Sphincter muscle strong and 
circumscribed. Mesenteries all complete. A weak ectodermal musculature on the 
column and stomodeeum. 
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 endoccele and exocele, 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 Discosome, 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 endocceles and exocceles, 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 defined 
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. 
