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



2. Stylodictya multispina, Haeckel. 



Stylodidya miiUispina, Haeckel, 1862, Monogr. d. Eadiol., p. 496, Taf. xxix. fig. 5. 

 Stylodictya furhesii, Ehreuberg, 187.5, Abhandl. d. k. Akad. d. AViss. Berlin, p. 160, Taf. xxiii. 

 fig. 6. 



All rings of the disk concentric, circular, of equal breadth. Pores regular, circular, two and a 

 half to three on the breadth of each ring. Eight to twelve radial beams beginning from the central 

 chamber, others from the inner rings. Commonly from the third ov fourth ring arise twenty-four 

 to thirty (sometimes forty or more) piercing beams, which are prolonged at the margin into bristle- 

 shaped radial spines, as long as the breadth of two to four rings. 



dimensions. — Diameter of the disk (with seven rings) 0-2 ; breadth of each ring 0'013 ; pores 0"004. 



Habitat. — Cosmopolitan ; Mediterranean, Atlantic, Indian, Pacific, surface and various depths. 



3. Stylodictya hastata, Ehrenberg. 



Stylodictya hastata, Ehrenberg, 1873, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 257 ; 



Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, Taf. xxiii. fig. 5. 

 Stylodictya gracilis, Bury, 1862, Polycystins of Barbados, pi. ii. fig. 1. 



All rings of the disk concentric, circular, of equal breadth. Pores regular, circular, very 

 small, two on the breadth of each ring. Eight to twelve marginal spines very large, spear-shaped, 

 sulcated, pyramidal, nearly as long as the diameter of the disk, with a thin pedicle at the base, 

 above this as thick as the breadth of one ring. 



Dimensions. — Diameter of the disk (with five rings) 0'13 ; breadth of each ring 0"012 ; pores 

 0003. 



Habitat. — Fossil in the rocks of Barbados. 



4. Stylodictya stellata, Bailey. 



Stylodictya stellata, Bailey, 1856, Amer. Journ., vol. xxii. p. 6, pi. i. fig. 20. 

 Stylodictya stellata, Haeckel, 1862, Monogr. d. Radiol., p. 499. 



All rings of the disk concentric, circular, of equal breadth. Pores regular, circular, very small, 

 two on the breadth of each ring. Mai-giual spines fourteen (probably variable in number, twelve 

 to sixteen), very thick and short, conical ; their length seems to be equal to their basal breadth and 

 to the breadth of one ring. Eelated to Stylochlamydium ? 



Dimensions. — Diameter of the disk (with five rings) Oil; breadth of each ring O'Ol; pores 0'003. 



HaMtat. — North Pacific, depths of the Kamtschatka Sea, Bailey; Station 241, depth 2300 fathoms. 



5. Stylodictya arachnia, Haeckel. 



Stylodictya arachnia, Haeckel, 1862, Monogr. d. Radiol, p. 497. 



Stylocyclia arachnia, 3. Miiller, 1856, p. 492; Abhandl. d. k. Akad. d. Wiss. Berlin, 1858, 

 p. 41, Taf. i. figs. 8, 9. 



All rings of the disk concentric, ckcular, or polygonal ; their breadth increases from the centre 

 towards the periphery, so that the fourth or fifth ring is twice as broad as the second. Pores 



