REPORT ON THE RADIOLARIA. 1245 



Subgenus 3. Hexaphormis, Haeckel, 1881, Prodromus, p. 432. 



Definition. Thorax with six radial ribs (three primary perradial and three second- 

 ary interradial beams). 



6. Setho2)hormis hexalactis, n. sp. (PL 56, fig. 6). 



Cephalis large, hemispherical, with irregular, polygonal pores. Thorax flatly campanulate, with 1 

 subregular, hexagonal pores, and six stout radial ribs ; the lateral connected in pairs. (Fig. 6 

 exhibits the central part of the shell, seen from below.) In the subcircular collar septum the two 

 anterior (jugular) meshes are much smaller than the two posterior (cardinal) meshes. The odd 

 anterior (sternal) rib is opposite to the posterior (caudal) rib. The two paired ribs of each side 

 (antero-lateral or pectoral and postero-lateral or ventral ribs) diverge from one common point. In 

 the specimen figured the left half of the thorax exhibited the two regular ribs, and the right half 

 three, a posterior accessory branch being developed (transition to Octophormis). This specimen- might 

 indeed be called ffeptapkormis heptalactis. 



Dimensions. Cephalis 0'02 long, 0'05 broad; thorax 0'08 long, Q - 22 broad. 



Habitat. Central Pacific, Station 274, depth 2750 fathoms. 



7 . Sethophormis hexagonalis, u. sp. 



Cephalis small, Hat, cap-shaped, with small, regular, hexagonal pores. Thorax flatly: conical^ 

 nearly discoidal, with larger pores of the same form, and six stout, straight, prominent ribs. 

 These arise at equal distances from the six corners of the hexagonal base of the collar septum. 

 Peristome hexagonal, with a corona of short spines. 



Dimensions. Cephalis 0'015 long, 0'04 broad; thorax 0'06 long, 0'24 broad. 



Habitat. North Atlantic, Station 354, surface. 



Subgenus 4. Octophormis, Haeckel. 



Definition. Thorax with eight radial ribs, four secondary interradial beams 

 being interpolated between the four primary perradial beams of Tetraphormis. 



8. Sethophormis octalactis, n. sp. 



Cephalis large, hemispherical, with irregular, polygonal pores. Thorax flatly campanulate, with 

 regular, hexagonal pores, and eight stout, regularly-disposed, radial ribs reaching the margin at 

 equal distances. Foxir of these correspond to the four primary ribs of Tetraphormis cruciata, and 

 exhibit at their base a larger pair of basal pores, surrounded by a semicircular ring (PL 70, fig. 5) ; 

 the other four are secondary, interpolated. Peristome circular, simple. 



Dimensions. Cephalis 0'03 long, 0'06 broad ; thorax 01 long, 0'22 broad. 



Habitat. Indian Ocean, Madagascar (Rabbe), surface. 



