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



9. Stylodictya centrospira, n. sp. (PL 41, fig. 9). 



Inner rings of the disk (three or four) convoluted in a simple or double spiral, often interrupted 

 or irregular ; outer rings (two to three) concentric, circular, or roundish. Breadth of the rings 

 variable, irregular. Pores irregular, of very different sizes, in the outer concentric part twice to four 

 times as large as in the inner spiral part. Eadial beams partly interrupted, partly piercing. 

 Marginal spuies fifty to eighty, very variable in size and numljer, commonly fifteen to twenty strong 

 conical spines, twice to three times as long as the ring-breadth, and numerous (thirty to sixty) smaller 

 spines. Very variable. 



Dimensions. — Diameter of tlie disk (with seven rings) 0-2 ; breadth of the rings 0-01 to 0'02 ; 

 pores 0-002 to 0-01. 



Habitat. — Pacific, central area. Stations 263 to 274, depth 2350 to 2925 fathoms. 



10. Stylodictya setigeixi, Ehrenberg. 



Stylodictya setige)-a,'EhTeBheTg, 187.5, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxiii. fig. 4. 



Inner rings of the disk (two to three) convoluted in a simple or double spiral, outer rings 

 (two to three) concentric, circular, or roundish. Breadth of the rings nearly et^ual. Pores regular, 

 circular, three on the breadth of each ring. Marginal spines twenty to forty, bristle-shaped, about 

 twice as long as the ring-breadth. (The specimen figured by Ehrenberg was a young one ; 

 in older specimens I found the inner spiral disk surrounded by two to three concentric circular 

 rings.) 



Dimensions. — Diameter of the disk (with six rings) 016 ; breadth of the rings 012 ; pores 0-003. 



Habitat. — Fossil in the rocks of Barbados; also living in the depths of the Central Pacific, 

 Station 266, depth 2*750 fathoms. 



Subgenus 3. Stylospira, Haeckel, 1862, Monogr. d. Eadiol., p. 515. 



Definition. — All rings of the disk convoluted in a simple or double spiral (some- 

 times also in quartered half-spirals). 



11. Stylodictya heliospira, n. sp. (PI. 41, fig. 8). 



Stylospira heliospira, Haeckel, 1879, MS. 



All rings of the disk convoluted in a simple regular spiral, increasing in breadth from the 

 centre towards tlie periphery ; the sixth ring twice as broad as the second. Pores irreg-ular, 

 roundish, two on the breadth of each ring. Marginal spines numerous, thirty to forty, bristle- 

 shaped, nearly half as long as the radius of the disk. 



Dimerisions. — Diameter of the disk (with seven rings) 0-16 ; breadth of the inner rings 0-008, 

 of the outer 0016 ; pores 0-002 to 0-006. 



Habitat. — Mediterranean, Portofino near Genoa, surface ; also fossil in the Tertiary rocks of 

 Sicily ; Caltanisetta, Haeckel. 



