THE ACTINIA NS OF PORTO RICO. 
363 
The mesenterial filaments occur on all the mesenteries except the members of the last cycle, 
and possess both ciliated and glandular streaks. The ciliated streak has only a very short course, 
disappearing from all the mesenteries a little below the level of the stomodseum. The acontia are 
crowded with narrow elongated nematocysts. 
The male and female reproductive cells occur in different individuals. Both are developed in 
enormous quantities on the second, third, and fourth mesenterial cycles. 
Lesueur (1817, p. 171) has described from the West Indies the two species Actinia tricolor and 
A. bicolor as distinct, and Duchassaing & Michelotti (1866, p. 234) have added a third, A. egletes. 
McMurrich (1898, p. 234), however, has discussed the validity of these three species, and finds that it 
is impossible to maintain their separation, a conclusion with which I agree. McMurrich has further 
decided that the Actinia sol, Agass. ms. (Verrill, 1874, p. 24), of the Carolina coast is indistinguishable 
from the West Indian species. Therefore the West Indies appear to possess but one species of 
Calliactis, with a range extending northward as far as the eastern coasts of the United States. 
In addition to Jamaica and Porto Rico, the species is now known from the following islands: 
Barbados ( A . tricolor), attached to shells tenanted by hermit crabs (Lesueur) ; St. Vincent (A. bicolor), 
adherent to shells (Lesueur); St. Thomas (A. egletes), upon shells and the carapace of the living 
Pericera cornuta (Duchassaing & Michelotti); Bahia, Cuba (McMurrich); also near Charleston, S. C. 
(Agassiz, Verrill). 
Order STICHODACTYLINtE Andres. 
Act.iniaria in which more than one tentacle may communicate with a mesenterial chamber. 
Usually a peripheral series of one or more cycles can be distinguished from an inner or accessory 
series, the members of which are radially arranged or in groups, and are often of different form. 
Sphincter muscle either endodermal or absent. 
Next to the arrangement of the mesenteries, the disposition and character of the tentacles has 
been found of great service for classificatory purposes in the Actiniaria. The proposal of Andres to 
separate the Hexactinix into two groups, Actininx and Stichodactylinx, according as only one tentacle 
or more than one may arise from a mesenterial chamber, has in the past met with universal acceptance. 
Beyond the mesenterial plan it is recognized that within different groups different characteristics may 
assume particular importance, especially for the minor subdivisions. No mesenterial distinction 
avails to separate the Actininx from the Stichodactylinx, and within the various families of the former 
no very great difference in the tentacular plan is presented, while great diversity occurs in the latter. 
Therefore in the Actininx the tentacles have not assumed that taxonomic importance which has been 
assigned them in the Stichodactylinx. In the former the character of the musculature has been found 
to be of greater utility in determining what may be considered natural relationships. 
In my paper on the Jamaica Stichodactylinx I refer to the great variation presented by the ten- 
tacular systems of the different genera there studied, and consider it very doubtful if there is much 
homologous connection among them; more likely they are polyphyletic. To my mind, however, 
one great distinction is recognizable, according as the tentacles are all of one form or of two forms; and 
for these I suggested the two suborders Homodctctylinx and Heterodaclylinx. 
The conception underlying the separation is altogether at variance with that which Carlgren 
is endeavoring to introduce, and in the “Nachschrift” to his “Ostafrikanische Actinien” (p. 116) he 
somewhat petulantly characterizes the division as “nicht viel besser, als wenn man die Actiniarien 
nacli der verschiedenen Zahl der Tentakelcyklen einteilen wollte.”' Carlgren naturally regards every 
proposal in the light of its relationship with his own scheme, according to which he is seeking to 
combine all the forms with primary characteristics to the neglect of their later modifications. The 
division referred to above is based wholly upon these latter, and regards thespecies retaining the primary 
characters as the lowest of their own particular group. For example, within the Stichodactylinx it 
is probably impossible to mention two species more widely divergent in their tentacular plan than 
Ricordea florida and Actinotryx sancti-thomx. In the former the marginal and inner tentacles are all 
of the same form, arranged in regular radial rows; in the latter the marginal tentacles are simple, and 
two or three orders are represented in a single cycle; the inner tentacles are dendroid, separated by a 
naked space from the marginal, and are arranged in a middle discal and a eircumoral group. Morpho- 
logically the two tentacular series — marginal and accessory— seem wholly unconnected with one another 
in Actinotryx, while they probably form a consecutive series in Ricordea. The tw r o species are alike, 
