190 



COELENTERATA. 



Section 6. Ceriantheae. 



With numerous unpaired mesenteries (Fig. 152), and a single gonidial groove 

 (ventral). The two mesenteries attached 



to the gonidial groove (directive) are 

 very small ; the mesentery on either 

 side of these is laige, and reaches to 

 the aboral end ; the remaining mesen- 

 teries diminish in size towards the dorsal 

 region where new mesenteries are added 

 (not ventrally as in Zoantlicae). 



Fam. Cerianthidae. With a double 

 corona of tentacles, marginal principal 

 and circumoral accessory ; aboral end 

 rounded ; without sphincter. With an 

 aboral pore and a sheath of mud, sand 

 grains, and nematocysts, in which the 

 aboral end of the body lies as in a 

 case. Cerianthus D. Chiaje ; Batliyan- 

 thus Moseley ; Arachnactis Sars, pelagic 

 (possibly a larval form). 



"-a, 



FIG. 152. Diagram of the arrangement of 

 the mesenteries of Cerianthus. a goni- 

 dial groove. 



Sub-order 2. ANTIPATHARIA.* 



Colonial Zoantharia with a tendency to hexamery ; with a usually branched, 

 axial, hollow, horny skeletal rod contained in an epithelial sheath. 



The coenenchyma consists of the fused bases of the polyps ; it is always thin 

 and without spicules. Except in one genus there is a central horny rod, round 

 which the coenenchyma is disposed. The origin of the epithelial sheath which 

 surrounds the rod is unknown. The polyps have generally six tentacles and six 

 primary mesenteries, four of which are directives, and the other two transverse. 

 The transverse mesenteries bear the gonads. The 4 or 6 secondary mesenteries 

 fade away in the lower part of the polyp. The polyps are always much elongated 

 in the transverse axis (i.e. at right angles to the elongation of the mouth), and 

 in the Schizopathinae the body is actually constricted into three divisions, two 

 lateral containing the gonads and one central with the mouth. Each division 

 has two of the tentacles. To this phenomenon the name pseudo-dimorphism 

 rather than dimorphism (gonozooids and gastrozooids) should lie applied. 



Fam. 1. Savagliidae. With 24 mesenteries and tentacles. The colonies are 

 without an axial rod, but form a sheath round Gorgonid skeletons. Polyps 

 with typical Actinian structure. Probably Actiniarians. Savaglia Nardo 

 (Gerardia L. Duth.). 



Fam. 2. Antipathidae. With 6 tentacles, 6 primary mesenteries, and with 

 or without 4 or 6 secondary mesenteries. The two lateral primary mesenteries 

 bear the gonads. The axial skeleton is spiny and has a central canal. 



Sub-fam. 1. Antipathinae. Polyps not pseudo- dimorphic, each with 

 6 tentacles ; transverse axis of the polyp more elongated than the axis 

 (sagittal) which is marked by the long axis of the mouth. Cirripathes 

 Blainv. ; Stichopathes Brook; Leioputhcs Gray; Antipathes Pall.; Anti- 

 pathella Brook; Aphanipathes Brook; Tylopathes Brook; Pteropathes 

 Brook ; Parantipathes Brook. 



* G. Brook, "Report on Antipatharia," Challenger Eeports, Pt. 80, 1889. 



