188 COELENTERATA. 



Sub-fam. 3. Phellinae. Sagartidae with a cuticular covering ; primary 

 mesenteries alone fertile. Phellia Gosse ; Octophellia And.; Ilyactis And.; 

 Ammonactis Verr. 



Fam. 10. Heteractidae. Tentacles clavate, knobbed. Eloactis And. ; Rhopo- 

 lactis And.; Ragactis And.; Heteractis M.-Edw. and H. ; Stauractis And. 



Fam. 11. Sideractidae. "With sixteen pairs of perfect mesenteries, and 

 three series of non-retractile tentacles, of which the innermost contains eight. 

 Sideractis Dan. 



Fam. 12. Madoniactidae. With a few principal mesenteries, acontia, and 

 a prominent endodernial circular muscular system. Intermediate between 

 Bunodidae and Sagartidae. Madoniactis Dan. 



Fam. 13. Andvakiadae. Elongated, without any real pedal disc, seated 

 loose in the sand, the greater part of the body encrusted. The uppermost bare 

 part of the body, the oral disc, and the tentacles completely retractile. Few 

 mesenteries. Endodermal circular muscular system. Near Sagartidae. 



Fam. 14. Liponemidae.* Tentacles reduced to short tubes or stomidia ; 

 with numerous perfect mesenteries. Deep-sea forms. Polysiphonia R. Hert., 

 tentacles short tubes with large terminal opening, allied to Paractidae ; Poly- 

 stomidium, R. Hert., with stomidia, allied to Actinidae ; Liponema R. Hertwig, 

 stomidia very numerous ; Aulorchis R. Hert., with gonads modified into a tube 

 opening through the mouth. 



Fam. 15. SarcophiantMdae. Sarcophianthus Lesson. 



Fam. 16. Thalassianthidae. Tentacles replaced by bushy excrescences of the 

 disc. Thalassianthus Leuck. ; Actineria Blain.; Megalactis Ehrb. ; Actinodendron 

 Blain. 



Fam. 17. Ilyanthidae. With single corona of tentacles ; pedal disc absent, 

 gonidial grooves and sphincter obscure. Ilyanthus Forbes ; Mesacmaea And. ; 

 Halcampa Gosse ; Halcampella And. 



Fam. 18. Siphonactinidae. Like the last, but with a gonidial groove, the 

 lips of which project beyond the mouth (conchula). Peachia Gosse ; Siphon- 

 actinia K. and D. ; Philomedusa Miiller ; Adinopsis K. and D. 



Danielssen's genera Aegir and Fenja^ do not exist. They were founded upon 

 mutilated specimens. 



Section 2. Paractinia. 



With paired mesenteries. There are two pairs of directives, and the longi- 

 tudinal muscles are arranged as in Hexactinia. Number of mesenteries has no 

 relation to the number 6. With two gonidial grooves and two oesophageal 

 lappets. 



Fam. 1. Sicyonidae. Sessile, with tetramerous arrangement of the mesenteries, 

 sphincter muscle mesodermal, tentacles as short knob-like stumps. Possibly 

 related to the Tetracorallia. Sicyonis R. Hert. Deep-sea form. 



Fam. 2. Polyopidae. Without pedal disc, tentacles transformed into 

 stomidia. J Polyopis R. Hert. Deep-sea form, probably tetramerous. 



* Vide note on p. 186. 



t D. E. Danielssen, "Actinida," The Norwegian North Atlantic Expedition 

 1876-8. 1890. 

 J See note on p. 186. 



