250 



T. A. STEPHENSON 



Dactylanthus, Carlgr., 1911, p. 2. 



Ptychodactidae with twenty-four tentacles. Body with twenty-four 

 vertical rows of hollow outgrowths or vesicles, corresponding to the 

 twenty-four regular endocoels and exocoels. Sphincter very weak 

 diffuse. Actinopharynx quite well developed, with two siphonoglyphes 

 and with curious pockets between the insertions of some of the mesen- 

 torios. Twelve pairs of Tiiesenteries, six pairs or all of them perfect, all 

 fusing together down below in the gonad region, in such a way that the 

 gonads occupy no longer the now non-existent free edge of the mesentery, 

 but the region nearest to the point of fusion. 



Species : 



I), antarcticus, Clubb, 1908, p. 5. (See Carlgren, 1911.) 



Tribe 3. Nynantheae, Carlgr. 



Usod lioro in a diffi^ront soiisp than that of Carlp;ren. so that 

 it oxcUnlpR Edwardsiivria, Corallimovpliidae, and Discosomidao, 

 hill inchidos Boloceroi dos and tho Endocoolactids. 



Aetiiviaria with or without a definite base, with or without basilar 

 muscles. Body-wall smooth or with verrucac or outgrowths of one sort 

 or another. The presence of a sheet of ectodermal muscle in body-wall 

 or actinopharynx is exceptional, occurring sporadically, and sometimes 

 reduced to a vestige such as ectodermal )nuscle in the siphonoglyphes. 

 Spirocysts in body-wall ectoderm are also exceptional save in Endo- 

 coelactaria. A sphincter may or may not be present, and if present 

 may be weak or strong, endodermal or mesogloeal. Tentacles few or 

 many, simple or complex, their longitudinal musculature ectodemial or 

 mesogloeal. Siphonoglyphes are typicalh' present. The mesenterial 

 filaments have ciliated tracts. Pairs of perfect mesenteries are present 

 save in abnormal cases, and usually at least six pairs, often more. Six 

 is a fundamental number for arrangement of parts, but there are a gootl 

 many de\aations. Mesenterial musculature does not often exhibit so low 

 ■ a grade as in Gonactiniidae, Ptychodactidae, and many IVIadreporaria — 

 often it is highly developed, very definitely marked off retractors being 

 formed — cases of weakness ai"e usually sporadic and secondary rather 

 than universal and inherent. 



Sub-tribe 1. Atiienaria, Carlgr. 



Used here as coverino; Halcampids and Tlyanthids hut not 



Edwardsians. 



Nynantheae representing those forms which being the outcome of 

 a Hal cam pa-like ancestor have retained more similarity to that 



