24 Coelenterata. 



lactis, ? ApiacttSj ? Peponactis. (3) Bo trucnidi ferae, with cnidorages. mostly 

 aggregated in botrucnidae ; no acontia; (a) Botrucnidifer n. g., with botrucnidse 

 in the most aboral part of protocn. 2, 3, and of macrocn. and brachycn. ; 

 metacn. and protocn. 2 with cnido-glandular tracts; protocn. 2 long and fertile; 

 M, B, m, b; in one specimen of norvegicus the mesenteries of the left side are 

 more developed than those of the right, the oral part of left protocn. 2 is 

 wanting, and its cnido-glandular tract has fused with protocn. 3 ; (b) Botruanthus, 

 with cnidorages dispersed irregularly over the craspedonemes and bunches, 

 cnido-glandular tract on protocn. 2, and on metacnemes M and m'?: M, b, m, 

 B; larval genera referred here - - Cerianthula , Hensenanthula , Calpanthula. 

 The characters of all known species of Ceriautharia are detailed in tabular 

 form. The arrangement of the tentacles and the structure of the stomodseum 

 are discussed. The ectoderm of the siphonoglyph contains, besides strongly 

 ciliated supporting cells, mucus-cells in abundance. The hyposulcus is usu- 

 ally short, but in Arachnanthus is longer than the stomodseum; its ectoderm 

 differs from that of the siphonoglyph only in containing fewer mucus-cells. Hemi- 

 sulci are absent in A, rudimentary in Botrucn., but in other genera are more 

 or less distinctly developed. In Ce. lloydii they are rounded in transverse 

 section, and correspond in structure to a median streak, i. e., they contain mucus- 

 cells and numerous spirocysts. In Ce. membranaceus the hemisulci are long 

 and flat, and connected with one border of the directive mesenteries; they are 

 strongly ciliated, consist chiefly of supporting cells, while mucus-cells, thick- 

 walled nematocysts and spirocysts are sparse. Intermediate between these, in 

 structure of its hemisulci, is Ceriantheopsis americanus. The author regards 

 (with van Beneden) the first 3 mesenteries on each side of the directive plane as 

 protocnemes; of these 1,1, are sterile, and usually without filaments; 2,2, 

 are either fertile or sterile [see above], if fertile they agree in length and 

 structure with the 1st and 2d cycle metacnemes, if sterile with the 3d and 4th 

 cycle metacn.; 3,3 are always sterile and resemble in structure the 3d and 

 4th cycle metacn. The metacn. are in quartettes, the components of which 

 exhibit different arrangements [see above]. All Ceriantharia examined by 

 the author are hermaphrodite, including Ge. borealis (= lloydii} and amer. 

 Pachyc. fimbriatus, though apparently an exception to this rule, is probably 

 also hermaphrodite, its two sets of gonads not being mature at the same time. 

 Certain Cerianthids are protandrously hermaphrodite. Probably in all Cerian- 

 tharia the longitudinal muscles of the mesenteries are on the sides of the 

 mesenteries looking away from the directive chamber, and the transverse muscles 

 on the sides facing that chamber. This probably holds good also for the usu- 

 ally indistinct muscles of the directive mesenteries. This arrangement, considered 

 in connection with that of the muscles of other Anthozoa, favours the view that 

 the directives (and the siphonoglyph) are dorsal in Ceriantharia. The Cerian- 

 tharia do not pass through an Edwardsia-stage; they have not a definitely 

 rnarked-off larval stage with 8 mesenteries; the demarcation between the protocn. 

 and metacn. is after the formation of the first 6 mesenteries. Further, the 

 4th couple of mesenteries in Actiniaria, Madreporaria and Zoantharia is a couple 

 of directives, whereas it is not in Ceriantharia. The latter are thus diffe- 

 rentiated at that stage from all other Zoantharia except Autipatharia. The 

 author calls attention to the likeness of a young Cerianthid larva to a primitive 

 Antipatharian. A mesenterial filament, at its commencement, immediately 

 below the stornodseum, consists of a middle cnido-glandular tract and of 2 lateral 

 ciliated tracts; the latter cease after some distance, and the c.-g. tract is con- 

 tinued aborally as a wavy structure. The two parts of the c.-g. tract are 



