1296 THE VOYAGE OF H.M.S. CHALLENGE!!. 



21. Sethoconus facetus, n. sp. (PI. 55, fig. 1). 



Phlebarachnium facetum, Haeckel, 1881,'Prodromus, p. 430. 



Cephalis small, hemispherical, with distinct collar septum, the same network as the thorax, 

 and numerous bristle-shaped horns of the same length. Thorax wide, conical, about as long as 

 broad, with slightly convex outlines ; its network extremely delicate, with very small and numerous, 

 regular, hexagonal pores, disposed in numerous divergent, longitudinal series, which are convoluted 

 somewhat spirally around the shell axis. Surface covered with thin, scattered, bristle-shaped spines, 

 about as long as the cephalis. 



Dimensions. Cephalis O02 diameter, thorax 02 long, 022 broad. 



Habitat. Central Pacific, Stations 271 to 274, surface. 



22. Sethoconus anthocyrtis, n. sp. (PI. 62, fig. 21). 



Anthocyrtis sethocomts, Haeckel, 1879, Atlas, loc. cit. 



Cephalis small, subspherical, with very small pores and numerous radial, bristle-shaped spines 

 of the same length. Thorax wide, conical, about as long as broad, with parabolic outlines, its net- 

 work very delicate, with subregular, hexagonal meshes. Surface with scarce, bristle-shaped spines 

 (not represented in the figure). Mouth with a corona of numerous small, vertical spines. 



Dimensions. Cephalis 0'025 diameter, thorax 026 long, O24 broad. 



Habitat. North Pacific, Station 248, surface. 



23. Sethoconus virgultus, n. sp. 



Cladaraclinium virgultum, Haeekel, 1881, Prodromus, p. 430. 



Cephalis and thorax nearly of the same form and stricture as in Sethocomis facetus, but larger 

 and wider, with the same delicate, hexagonal network (PI. 55, fig. 1) ; it differs from the latter by 

 the wider, more convex and campanulate form, but mainly by the armature of the surface, which is 

 densely covered with thin, arborescent, bristle-shaped spines, irregularly branched, and four to eight 

 times as large as the cephalis. 



Dimensions. Cephalis 0'02 diameter, thorax O32 long, 0'4 broad. 



Habitat. South Pacific, Station 288, surface. 



24. Se,thoconus setosus, n. sp. 



Phltbarachnium setosum, Haeckel, 1881, Prodromus, p. 430. 



Cephalis small, subspherical, with distinct collar septum, and the same network as the thorax, 

 with numerous bristle-shaped horns of the same length. Thorax slenderly conical, twice as long as 

 broad, with irregular, polygonal pores of little different sizes, and very thin bars. Surface covered 

 with perpendicular, simple, bristle-shaped spines, about as long as the cephalis. 



Dimensions. Cephalis 0'02 diameter, thorax 012 long, 0'22 broad. 



Habitat. Central Pacific, Stations 266 to 272, surface. 



