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



1. Thalassoxanthium triactinium, n. sp. 



Spicula all (or nearly all) triradiate, composed of three (or sometimes iu a few spicula four) 

 needle-like shanks of equal length, diverging from one common point. Shanks straight or somewhat 

 curved, smooth, pointed. Central capsule pellucid, twice as broad as its dark nucleus, without 

 larger oil-globules. Jelly-envelope very thin, with numerous xanthellse. 



Dimensions. Diameter of the central capsule 01, of its nucleus 0'05, length of the spicule- 

 shanks 0'6 to O8. 



Habitat. Central Pacific, Station 266, surface. 



2. Thalassoxanthium triradiatum, n. sp. 



Spicula all (or nearly all) triradiate, composed of three (or sometimes in a few spicula four) 

 needle-like shanks of different length, diverging from one common point. Shanks curved or 

 bent, covered with small conical thorns. Central capsule dark, three times as large as the 

 nucleus, with numerous large oil-globules. Jelly-envelope thick, without xanthellse. 



Dimensions. Diameter of the capsule O2, of the nucleus O07, length of the spicule-shanks 

 01 to 015. 



Habitat. South Pacific, Station 302, surface. 



3. Thalassoxanthium medusinum, n. sp. (PI. 2, fig. 5). 



Spicula all (or nearly all) quadriradiate, irregular, composed of four (or sometimes in a few 

 spicula three) needle-like shanks (mostly of unequal length), diverging from one common point. 

 Shanks curved, pointed, thorny, covered with small spinules. Central capsule dusky, twice to three 

 times as large as its dark central nucleus. On the inside of the membrane numerous large oil- 

 globules. Jelly-envelope thin, with numerous xanthelLie. 



Dimensions. Diameter of the central capsule 0'45 to 0'5, of its nucleus 018 to 0'2. 



Habitat. North Pacific, Station 244, surface. 



4. Thalassoxanthium hexactinium, n. sp. 



Spicula all (or nearly all) hexaracliate, composed of six (or sometimes in a few spicula three) 

 needle-like shanks, diverging in two opposite hemispheres (three needles upwards, three needles 

 downwards). Shanks somewhat curved, pointed, smooth. Central capsule yellowish-brown, dark, 

 four times as broad as its dark central nucleus. Jelly-envelope thick (about twice as broad as the 

 capsule), with very numerous xanthella?. 



Dimensions. Diameter of the central capsule 0'3 to 04, of its nucleus 01 to 012. 



Habitat. South Atlantic, Station 325, surface. 



