Hapvpon—The Actiniaria of Torres Straits. 469 
Family.—Discosomipm, Klunz. 
Stichodactyline, with the column either smooth or furnished with verruce 
towards its upper portion. Oral disk usually of large size and lobed. ‘Tentacles 
all of one kind, varying in form from long, slender, and pointed to very short and 
blunt; accessory tentacles in numerous radial rows or groups. Very numerous 
mesenteries, many of which are perfect; all the larger mesenteries are fertile 
(except the directives?). Sphincter muscle endodermal, strong, and circumscribed, 
more or less feebly developed, or absent. 
Simon (Ein Beitrag zur Anat. und Syst. der Hexactinien Inaug.-Dissert. 
Miinchen, 1892), who has studied the type species of Discosoma (D. nummiforme 
; ; Ype Ss} 
and D. tapetum), gives the following table (p. 92) :— 
“J. On the very broad oral disk the tentacles are arranged in numerous radial 
rows, both in the exoccels (Interseptal-) and endoceels (Intraseptal-kammern) :— 
a. Tentacles like papillee: 
Discosoma nummiforme (small form). 
Body-wall smooth ; border of oral disk somewhat undulating ; diffuse 
endodermal sphincter. 
D. fungiforme. 
Body-wall smooth ; border of oral disk lobed. 
b. Tentacles short, finger-like. 
D. anemone (large form), 
Body-wall, with suckers above ; border of oral disk almost even ; 
circumscribed endodermal sphincter. 
II. On the slightly extended oral disk the tentacles are disposed in radial 
groups in the endoceels only. 
a. Tentacles like papillee : 
D. tapetum (moderate-sized form). 
Body-wall smooth, oral disk rounded ; no sphincter. 
b. Tentacles short, finger-like (and club-shaped). 
D. giganteum (large form). 
Body-wall smooth ; border of oral disk distinctly lobed. 
(D. molle ?).” 
This family will require a good deal of working at before it can be 
