1296 THE VOYAGE OF H.M.S. CHALLENGER. 



21. Sethoconiis facetus, n. sp. (PL 55, fig. 1). 



PJilebarachnium facefum, Haecke], 1881, ProJromus, 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. 



Dimoisions. — Cephalis 0'02 diameter, thorax 0'2 long, 0-22 broad. 



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



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



Antliocijrtis sethoconus, Haeckel, 1879, Atlas, loe. 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 outhnes, its net- 

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

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



Dimensions. — Cephalis 0'025 diameter, thorax 0'26 long, 0"24 broad. 



Habitat. — North Pacific, Station 248, surface. 



23. Sethocorms virgultus, u. sp. 



CladaracJiniiun virgultum, Haeckel, 1881, Prodroiuus, p. 430. 



Cephalis and thorax nearly of the same form and stricture as in Sethoconus facdus, 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 0'32 long, 0'4 broad. 



Habitat. — South Pacific, Station 288, surface. 



24. Sethoconus setostis, n. sp. 



Phlebarachniam seiosum, 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. 



