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



smooth. Central capsules sx^lierical, small, with one central oil-globule. This species may be 

 regarded as the social form of Tlialassoxanthium, hexactinium. 



Dimensions. — Diameter of the central capsule 0-06 to O'OS, length of the spicula-shanks 0-05 

 to 0-06. 



Hahitat. — North Atlantic, FiBroe Channel (Gulf Stream), John Murray. 



Subgenus 2. Sphcerozonoceras, Haeckel. 



Definition. — Spicula all geminate-radiate, consisting of one middle rod, wliicli 

 bears an equal and constant number of rays (two, three, or four) at each end. 



5. SphoBrozoum furcatu7n, n. sp. 



Spicula all (or nearly all) geminate and simply forked, composed of a simple axial rod and 

 two smiple needle-like shanks on each end of it. Slianks straight, pointed, smooth, commonly some- 

 what longer than the middle rod. 



Dimensions. — Diameter of the central capsules O^l to 0'15, length of the axial rod of the spicula 

 0-03, of its shanks 0-04 to 0-06. 



Habitat. — Tropical zone of the Atlantic, near Ascension Island, Station 344, surface. 



6. SphcBrozoum furcidosiim, n. sp. 



Spicula all (or nearly all) geminate and simply forked, composed of a simple axial rod and 

 two simple needle-like shanks on each end of it. Shanks curved or bent, pointed, thorny, witli 

 many small spinides, conunouly somewhat shorter than the middle rod. 



Dimensions. — Diameter of the central capsules 0'2 to 0'25, length of the axial rod of the spicula 

 O-l, of its shanks 0-05 to 0-08. 



Hahitat. — South Atlantic, near Tristan da Cunha, Station 334, surface. 



7. SphcBrozoum ovodimare, Haeckel. 



Sphcerozoum ovodimare, Haeckel, 1862, Monogr. d. Eadiol., p. 527, Taf. xxxiii. figs. 5, 6. 

 Sphceivzoum pundatum, var., Brandt, 1881, jMonatsber. d. k. preuss. Akad. d. Wiss. Berlin, Taf. i. 

 fig. 54. 



Spicula all (or nearly all) geminate and triradiate, composed of a long simple axial rod and 

 three simple needle-like shanks on each end of it. Shanks straight, pointed, smooth, commonly 

 shorter than the middle rod. (Often few furcate or four-rayed spicida are intermixed, or few 

 .spicula are not smooth, but thorny.) 



Dimensions. — Diameter of the central capsides 0"05 to 0"2, length of the middle rod of the 

 spicula 0-02 to O'OG, of its shanks 0-01 to 0-04. 



Hahitat. — Mediterranean, Naples, Messina, Haeckel ; Atlantic, Canary Islands, Cape Verde 

 Islands, West Coast of Africa, Stations 351 to 354; surface. 



