488 Hapvpon— The Actiniaria of Torres Straits. 
appearances of the sphincter are shown in PI. xxxu., figs. 8 and 4. This kind 
of sphincter is more of the type to which I have elsewhere applied the term 
“restricted.” 
The mesenteries are very numerous, and a large, but apparently indefinite, 
number are perfect; all the mesenteries which attain a certain size may bear 
gonads, but probably not the directives. 
THALASSIANTHUS, Leuck. 
Thalassianthide, with the margin of the oral disk thrown into long permanent 
lobes, which have the appearance of tentacles, and each of which bears a few 
serrated tentacles on its oral aspect, and a group of globular tentacles on 
its aboral aspect; the serrated tentacles may also occur on the oral disk 
proper. 
Kwietniewski is the only zoologist who has investigated the anatomy of a 
member of this genus. He finds, in 7. Senckenbergianus, ‘‘ Actiniaria von Ternate,”’ 
Abhandl. Senckenbergisch. naturf. Ges. xxui., 1897, p. 337, that there are no 
directives, and an irregular number of perfect and imperfect mesenteries which 
have no definite arrangement. All the large mesenteries bear gonads. There is 
a circumscribed endodermal muscle with a stout mesogloeal axis. 
T. aster. Leuck. T. Senckenbergianus, Kwietn. 
Family.—AcTINODENDRIDA, n. f. 
Stichodactyline of large size, with a smooth body-wall; oral disk produced 
into a number of long tentacle-like arms, which bear variously disposed dendritic 
or globular tentacles. Mesenteries few in number, and arranged on the ordinary 
Hexactinian plan; they are all fertile, with the probable exception of the 
directives; no sphincter muscle. 
My studies on the type genus of this new family have rendered it quite ap- 
parent that Actinodendron must be finally separated from the genera Thalassianthus 
and Actineria with which they have been united since the days of Milne-Edwards. 
Kwietniewski (‘‘ Actiniaria von Ternate,” 1897) has also arrived at a similar con- 
clusion; and he suggests (p. 3837) the new family Dendrianthidz (which he does 
not define at all) for the genus Megalactis. Somewhat later in his inaugural 
dissertation, ‘‘ Kin Beitrag zur Anatomie und Systematik der Actiniarien” (Jena, 
