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



smooth. Central capsules spherical, small, with one central oil-globule. This species may bo 

 regarded as the social form of Thalassoxanthium hexactinium. 



Dimensions. Diameter of the central capsule 0'06 to 0'08, length of the spicula-shanks 0'05 



to 0-06. 



Habitat. North Atlantic, Faroe Channel (Gulf Stream), John Murray. 



Subgenus 2. Sphcerozonoceras, Haeckel. 



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

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



5. Sphcerozoum furcatum, 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 straight, pointed, smooth, commonly some- 

 what longer than the middle rod. 



Dimensions. Diameter of the central capsules 01 to 015, 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. Sphcerozoum furculosum, 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, with 

 many small spinules, commonly 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 

 01, of its shanks 0'05 to 0"08. 



Habitat. South Atlantic, near Tristan da Cuiiha, Station 334, surface. 



7. Sphcerozoum, ovodimare, Haeckel. 



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

 Sphcerozoum punctatum, var., Brandt, 1881, Monatsber. d. k. preuss. Akad. d. \Viss. 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 spicula are intermixed, or few 

 spicula are not smooth, but thorny.) 



Dimensions. Diameter of the central capsules 0'05 to 0'2, length of the middle rod of the 

 spicula 0-02 to 0'06, of its shanks O'Ol to 0'04. 



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

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



