CLASSIFICATION OF ACTINIARIA 551 
Sub-eclass ZoANTHACTINIARIA. Orders included: 
Edwardsiaria, Zoanthinaria, Dodecacti- 
niaria. Common characters or tendencies, 9. 
1. Directive mesenteries typically present, two pairs the standard 
number. 2. The directive endocoels do not become subdivided in 
most forms, but it may occur. 3. There are always more than eight 
mesenteries, even if only eight strong ones, in adults. 4. The eight 
protocnemes do not typically get pushed out of the way in the manner 
typical of Ceriantharia. 5. In most cases the mesenteries form pairs, 
not couples. 6. There are never just eight pinnate tentacles ; pinnate 
tentacles at all are rare, and occur in a few forms of obvious relation- 
ships. 7. There are no gular tentacles like those of Cerianthids. 
8. There is no sheet of muscle in the body-wall ectoderm comparable 
in strength to that of Cerianthids. 9. There is no horny axis like that 
of Antipatharia. 
Order DopEcCACTINIARIA. Sub-orders included: Madre- 
poraria, Actiniaria. Common characters or 
tendencies, 6. 
1. More than eight mesenteries, but there may be only eight 
perfect : but even so some imperfect ones pair with them: usually 
at least six pairs perfect. 2. After the first six couples, typically 
pairs in cycles are formed. 3. Both pairs of directives, if present, 
are perfect, not one pair macro- and the other micromesenteries as 
in Zoanthids. 4. The later mesenteries are not typically confined to 
two lateral regions of growth only, as in Zoanthids, though they may 
come in the directive endocoels. 5. Mesenteries not typically formed 
in unequal pairs, one perfect and macromesenteric and the other 
not, as in Zoanthids. 6. No canals in the body-wall save in the case 
of some skeleton-building forms. 
Sub-order ActintarntA. Tribes included: Protantheae, 
Ptychodacteae, Nynantheae. Common char- 
acters or tendencies, 6. 
1. No horny or limy skeleton. 2. No colonies. 3. Sting-cells of 
Madreporarian type do not occur much. 4. Tendency to muscularity 
greater than in Madreporaria, but not found in the most primitive 
forms and some others. 5. Siphonoglyphes present in the majority, 
but not in certain primitive and other forms. 6. Save in the earlier 
forms, the mesenterial filaments have ciliated tracts. 
Tribe ProrantHEak. 1 family. See Gonactiniidae for char- 
acters. 
