864 ' 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
however, in the absence of a basilar muscle, ciliated streak, and gonidial grooves, and each possesses 
only a weak musculature. On account of these characteristics, to the neglect of the tentacular 
divergences, they are classed together by Carlgren in the one family Discosomidx. 
Recognizing them as forms which retain the ancestral attributes just mentioned, but in other 
respects have become widely divergent, I see nothing illogical in considering Ricorda and Actinotryx, 
respectively, as among the lowest members of the two suborders llomodactylinx and Heterodadylinx , 
and for the present I propose to retain the two subdivisions. 
Suborder HOMODACTYUNE. 
Stichodactylinx in which the tentacles are all of one kind, simple or complex, and usually follow 
one another in continuous radial rows. 
Family STOICHACTIDtE Carlgren. 
tiloichactidse, Carlgren, 1900, p. ‘278; 1900a, p. '72 (also p. 119). 
Stichodactylinx with a basilar muscle and well-developed basal disk. Sphincter always present, 
shortly diffuse or circumscribed, usually not strongly developed, with well-marked gonidial grooves 
and ciliated streaks. Column usually provided with a distinct fossa and adhesive verrucse. Longi- 
tudinal musculature of the mesenteries well developed. The separation of the tentacles into a marginal 
and a discal series not pronounced; only one tentacle arises from each exoccele; tentacles simple or 
branched, sometimes swollen at the apex, never arranged in groups, nor as arm-like prolongations of 
the disk. 
Reviewing the family Discosomidx (1900, p. 155) I state: “As the Aetiniaria of tropical regions 
are more studied, the genera embraced under this family become more and more numerous ... it 
will be seen that the family includes a very heterogeneous assemblage of forms, corresponding in this 
respect with the Sargartidse among the Actinium. The only constant feature appears to be that the 
tentacles are all of the same form in any one species, and cover the greater portion of the disk; but 
apparently in no two genera are the peripheral and the inner tentacles similarly related. It will 
probably be found advisable later to separate as subfamilies forms in which only one row of tentacles 
communicates with a mesenterial chamber from those in which, as in Actinoporus, two or more rows 
may originate from the same mesenterial chamber.” 
At this time Carlgren was working upon a large assemblage of Stichodactylinx, including 
specimens of the Jamaica representatives which 1 was able to send him. The papers of Haddon 
(LS98) and Kwietniewski (1897, 1898), describing many new forms, had also appeared. Carlgren was 
therefore in a most favorable position for carrying forward the classification of the group, and this he 
has accomplished in a very elaborate manner. His first suggestions are contained in a short paper, 
“Zur Kenntnis der Sticliodactylinen Actiniarien” (1890), followed the same year by that on the 
“ Ostafrikanische Aetinien.” In these the value assigned the family distinction is very diverse. 
In some instances Carlgren chooses to attach supreme importance to the characters of anatomy and 
histology alone, and thus brings together many forms (e. g., Ricorda, Actinotryx ) allied in anatomical 
and histological details, but outwardly most diverse, while in other cases — Stoichactis, Homoslichanthus, 
and Actinoporus — new families, almost alike in their anatomyand histology, are constituted mainly 
upon tentacular differences. 
In the first paper he defines the families Discosomidx, Stoicliactidx, and Aurelianidx. The first 
includes forms without basilar muscle, ciliated streak, and gonidial grooves, and with weak mesenterial 
musculature, and embraces the genera Discosoma (1). nummiforme, type), Or in in, Ricordea, Actinotryx, 
and Rhodactis, thus including the most heterogeneous tentacular plans. The Stoicliactidx and Aureli- 
anidx include forms in which all the organs just mentioned occur and in which the mesenterial 
musculature is better developed. Along with these, and mainly distinguished by their tentacular 
arrangement and form, are the Plngmanthidx, Heteranthidx, ThalassiantMdx, and Actinodendridx. 
The family Sloichaclidx is defined above. It includes the genera Stoichactis, Radianlhus, Helian- 
thopsis, and Antheopsis. Carlgren has been able to compare the form I identify as the West Indian 
Actinoporus elegans with the European Aureliania, and, contrary to what I formerly expected from 
Gosse’s description and figure, shows that they agree very closely. The two genera constitute the 
family Aurelianidx. 
