REPORT ON THE RADIOLARIA. 1293 



10. Sethoconus nassa, Haeckel. 



Eucyrtidium nassa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 9. 



Cephalis slenderly ovate, with sharp collar stricture, few scattered pores, and a very stout, pyra- 

 midal horn of the same length, which is surrounded at the base by three short, divergent, ascending 

 spines (perhaps the remnants of the three cortinar rods of Eiwecryplialus, &c. ?). Thorax slender, 

 conical, with straight outlines, and small, dense, regular, circular pores of equal size. 



Dimensions. Cephalis 0'04 long, 0'02 broad ; thorax 012 long, 0'08 broad. 



Habitat. Fossil in Barbados. 



11. Sethoconus tabulatus, Haeckel. 



Cydadophora tabulata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, 



Taf. iv. fig. 18. 



Cephalis subspherical, with slight collar stricture, and numerous small, irregular pores, without 

 horn, or with a small conical horn. Thorax slenderly conical, with straight outlines, and large, 

 regular, hexagonal pores. Mouth truncate. (In the specimen I examined the thorax was longer 

 and more conically dilated ; the cephalis had a distinct small horn.) 



Dimensions. Cephalis 0'02 long, 0'03 broad ; thorax 0'08 long, 0'06 broad. 



Habitat. North Atlantic, Antilles, depth 1600 fathoms (Ehrenberg); Station 347, depth 2250 

 fathoms. 



Subgenus 2. Cornutettium (vel Ceratar actinium), Haeckel, 1881, Prodromus, p. 430. 



Definition. Cephalis very small, rudimentary, hyaline, without distinct collar 

 septum, and without pores (or with scarce, rudimentary pores). Thorax smooth. 



12. Sethoconus hexagonalis, Haeckel. 



Cornutella troclms, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 14. 



Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the 

 length. Thorax slenderly conical, or bottle-shaped, twice to three times as long as broad ; in the 

 lower half nearly cylindrical, with very thin, thread-like bars, and regular, hexagonal pores, 

 increasing in size towards the mouth. 



Dimensions. Cephalis O'OOS diameter, thorax 012 long, 0'05 broad. 



Habitat. Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen). 



13. Sethoconus verrucosus, Haeckel. 



Cornutella verrucosa, Ehrenberg, 18 

 fig. 16. 



Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the 



Cornutella verrucosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. is. 

 fig. 16. 



