REPORT ON THE RADIOLARIA. 1255 



Thorax broad, pyramidal, with slightly concave lateral outlines and nine (sometimes eight or ten) 

 curved ribs, which are connected by eighteen to twenty-four complete transverse rings. The large 

 meshes, so produced, have the form of a parallel trapezoid, and are in the eighth transverse row 

 three times as broad as long. (Differs from Batliropyramis trapezoides, PL 54, fig- 3, mainly by the 

 possession of a well developed cephalis). 



Dimensions. — Cephalis 0-04 long, 0'03 broad ; thorax (with eighteen rings) 0'32 long, 0'24 broad. 



Habitat. — South Pacific, Station 285, depth 2375 fathoms. 



7. Sethopyramis spinosa, n. sp. 



Shell thorny, slender, pyramidal. Cephalis small, subspherical, with few small pores and a 

 straight, vertical, conical horn twice the length. Thorax with nine straight ribs, which are con- 

 nected by sixteen to twenty complete transverse nine-angled rings. The large meshes so produced 

 are subregular, square. From each nodal point a short conical spine arises. (Differs from the 

 similar Bathropyramis spiriosa, PI. 54, fig. 4, by the development of the cephalis and the simple 

 pointed, unforked spines.) 



Dimensions. — Cephalis 0-03 diameter ; thorax (with sixteen rings) 0'2 long, 012 broad. 



Habitat. — Central Pacific, Station 263, depth 2650 fathoms. 



8. Sethopyramis hexagonalis, n. sp. 



Shell papillate, slender, pyramidal. Cephalis small, hemispherical, with a straight conical 

 horn twice the length, and small circular pores. Thorax conical, with slightly convex outlines and 

 nine stout, somewhat curved ribs in zig-zag form, which are connected by ten to twelve interrupted 

 transverse bars. From each nodal point a small conical papilla arises. The large meshes so pro- 

 duced are regular, hexagonal, gradually increasing in size towards the mouth. 



Dimensions. — Cephalis 0'03 diameter ; thorax (with twelve transverse rows of meshes) 0'18 long, 

 012 broad. 



Habitat. — South Atlantic, Station 335, depth 1425 fathoms. 



9. Sethopyrami.s cydomma, n. sTp. 



Shell thorny, slender, pyramidal. Cephalis large, subspherical, with numerous very small 

 circular pores, and a small conical horn of the same length. Thorax similar in form and structure 

 to that of the preceding species ; but each hexagonal mesh is provided with a very thin circular 

 hyaline ring (like a diaphragm), so that the openings are not hexagonal, but circular. From each 

 nodal point a short pointed conical or slightly forked spine arises. 



Dim.ensions. — Cephalis 0'02 diameter ; thorax (with ten transverse rows of meshes) 018 long, 

 014 broad. 



Habitat. — Tropical Atlantic, Station 348, depth 2450 fathoms. 



