470 Havpon—The Actiniaria of Torres Straits. 
satisfactorily classified. The four following genera appear to form a sequence ; 
probably (D.) giganteum will be the type of a new genus :— 
Sphincter absent ; no verruce ; tuberculiform tentacles. 
Discosomoides: type, D. tapetum, Ehr. 
Sphincter diffuse; no verruce ; tuberculiform tentacles. 
Discosoma: type, D. nummiforme, Leuck. 
Sphincter restricted ; with verrucze; pointed long or short tentacles. 
Radianthus: type, R. Kuekenthali, Kwietn. 
Sphineter circumscribed ; with verrucz ; pointed or blunt, moderately short 
or very short tentacles. 
Stoichactis: type, S. Kenti, Hadd. 
DISCOSOMOIDES, n. g. 
Discosomidze, with a smooth column and tuberculiform or papilliform tenta- 
cles; no gonidial grooves; numerous perfect mesenteries, all of which, excepting 
perhaps the directives, are fertile; sphincter muscle absent. 
D. tapetum, Eby. 
DISCOSOMA, Leuck. 
Discosomide, with a smooth column and tuberculiform or papilliform tentacles ; 
no gonidial grooves; numerous perfect mesenteries, all of which, excepting perhaps 
the directives, are fertile; diffuse endodermal sphincter muscle. 
D. numiniforme, Leuck. 
RADIANTHUS, Kwietn. 
Discosomide, with prominent verrucee in the upper part of the body-wall. 
Oral disk broad and somewhat lobed, with numerous, pointed tentacles ; marginal 
tentacles arranged in several cycles; accessory tentacles in numerous, radial, 
single rows; each row consists of more or fewer tentacles, according to the rank of 
the mesenterial chamber into which they open; two deep gonidial grooves. Mesen- 
teries in numerous cycles, most of which are perfect ; only the smallest mesenteries 
are sterile. Sphincter endodermal more or less diffuse (restricted*). 
Dr. Kwietniewski has anticipated me in the naming of this genus, as I had 
*For the meaning of this term cf. p. 432. 
