136 J. E. DurrpEn—Jamaican Actiniaria : 
only a single tentacle communicates with a mesenterial chamber) and Stichodacty- 
linee (in which more than one tentacle may communicate with a mesenterial 
chamber), has the advantage of being founded upon an external character which 
can be readily observed, and which must certainly be regarded as of some funda- 
mental importance in Actinian morphology. 
For better comparison of the tentacular relationships, I give a plan of a 
portion of the disc in each case. 
It is doubtful as to how far the Stichodactylinous condition is homologous 
throughout the order, for important differences obtain in each of the seven species 
to be described. 
In the Phymanthide the marginal tentacles are in numerous, alternating, 
entacmzeous cycles, arranged exactly as are the tentacles in the Actinine. The 
inner, so-called tentacles are nothing more than mere discal tubercles, more or 
less irregularly arranged, and histologically differ entirely from the outer 
series. Irom the evidence afforded by its peripheral tentacles, I regard the 
family as approaching the Actininz more closely than any of the others. 
The arrangement is somewhat similar in Actinotryx, but the marginal 
tentacles are all in a single cycle, though they probably represent two or three 
series for some reason not separated centripetally. The disc tentacles are 
irregularly arranged with regard to the mesenterial chambers ; and their dendritic 
form is perhaps but an exaggeration of the tubercular tentacle of Phymanthus. 
The arrangement of the outer and inner groups in Actinotryx recalls that in 
Corallimorphus, though the form of the tentacles presents a great contrast. 
The case of Corynactis is otherwise. So far as my experience goes, no 
distinction can be made between a peripheral and an inner series, though Haddon 
(1898, p. 466) makes a generic character of such a separation. The tentacles in 
each radial series follow one another in regular sequence, and afford the same 
histological details, pointing to a common origin; the relative sizes are, however, 
the reverse of those in the Actinine, 7c. the inner are the smaller, and the outer 
the larger. 
A somewhat similar arrangement holds in the genera Stoichactis and Ricordea. 
The tentacles in the same radial row follow one another in a regular manner ; but 
with regard to the conditions at the margin, however, the species vary. In 
Stoichactis helianthus a single outermost cycle alternates with all the radial rows. 
In Ricordea florida, on the other hand, the outermost cycle but one alternates with 
all the rows within, and with the cycle peripheral to it; these two marginal cycles 
are somewhat larger, and are often of a colour distinct from that of the inner 
tentacles. 
Homostichanthus possesses about a dozen outer cycles of tentacles, often 
distinguished from the inner series by the innermost cycle beimg differently 
