The Actiniae of the Plate Collection. 275 



of the specimens but a label accompanyiiig' No. 627 stated tliat in 

 life tliey were orange, yellow, red and wliile, while the Ivabel with 

 No. 628 described them as pure white. 



Strnr-ture. The mesog-h)ea of the column wall is slig-htly 

 thicker than the ectoderm and has a fibrillar strncture. The 

 ectoderm is higher than usual, however, the cells coniposing- it being 

 slender, so that the mesog'loea is really mach thicker than is usual 

 in Sag-artians of the size of the present forms. The circular mus- 

 culature is moderately developed and there is a stroug sphincter 

 (Fig. 64). It is ti-iangular in form and beautifully reticnlar 

 throughout; in its upper part it occupies practically the entire 

 thickness of the mesogloea, tapering off below very gradually toward 

 the endoderm, from which it is separated throughout by a thin layer 

 of mesogloea. 



The longitudinal muscles of the tentacles and the radial muscles 

 of the disc are moderately developed and entirely ectodermal in 

 l)Osition. The stomatodaeum is provided with numerous high longi- 

 tudinal lidges and has two rather shallow siphonoglyphs. 



The mesenteries are arranged hexamerously in four cycles, of 

 which the first two are perfect and include two pairs of directives. 

 Representatives of a fifth cycle are present in some of the exocoels, 

 but the cycle is never complete. Muscle pennons of moderate size 

 (Fig. 65) are present on the perfect mesenteries. while those of the 

 third cycle are small and those of the fourth cycle practically 

 wanting. The parieto-basilars may form a sliglit fold, but there 

 are practically no mesogloeal processes for the support of muscle 

 fibres external to the fold. Oral stomata were quite evident but 

 no marginal ones could be distinguished. Acontia were present, but 

 were not numerous; no reproductive organs were developed in the 

 specimen examined. 



The same reasons which led to the assignment of Actinia 

 impatiens to the Sagarfiinac hold with regard to the present species, 

 which seems on the whole closely related to impatiens, although it 

 is evidently a distinct species. 



Subfamily Mctridiinae ÜARLaßEN 1898. 



Sagartiidae with a relatively thin column wall, perforated by 

 cinclides; only the primary cycle of mesenteries perfect. 



