REPORT ON THE RADIOLARIA. 881 



3. Ilcxacolpus trypanon, n. sp. (PI. 140, fig. 11). 



Six hydrotomical spines of unequal size, two equatorial about as long as the diameter of the 

 shell and nearly twice as large as the four polar ; all of the same form, quadrangular prismatic, 

 with prominent edges and pointed distal ends. Sheaths six-sided prismatic, with strong prominent 

 edges and thinner parallel ribs between them ; their distal mouth with six strong denticulated 

 teeth. The sheaths envelop two-thirds of the spines, and are as broad as the radius of the 

 shell. 



Dimensions. Diameter of the shell 013 ; length of the equatorial spines 012, of their sheaths 

 0-08 ; breadth of the latter 0'06. 



Habitat. South Pacific, Station 288, surface. 



4. Hexacolpus dodecodus, n. sp. 



Six hydrotomical spines of unequal size, two equatorial about as long as the radius of the shell 

 and twice as large as the four polar ; all of the same form, triangular, compressed, sulcated. Sheaths 

 prismatic, with twelve prominent, parallel edges, and twelve strong serrated triangular teeth on the 

 mouth. The sheaths envelop the basal half of the spines. This species greatly resembles 

 Hexaconus serratus (PL 139, fig. 4), but differs in the larger size of the equatorial spines and the 

 complete reduction of the fourteen smaller spines. 



Dimensions. Diameter of the shell 0'2 ; length of the equatorial spines 01, of their sheaths 

 0'06 ; breadth of the latter 0'08. 



Habitat. North Pacific, Station 248, surface. 



5. Hexacolpus infundibuhim, n. sp. (PI. 140, fig. 10). 



Six hydrotomical spines of unequal size, two equatorial about twice as long as the diameter of 



Dimensions. Diameter of the shell 01 to 013 ; length of the equatorial spines 015 to 0'2, of 

 the shell and as the four polar spines ; all six spines of the same form, quadrangular prismatic, 

 pointed at the distal pyramidal end. Sheaths conical, two to three times as broad at the denticulate 

 distal mouth as at the narrow base, sulcate ; the mantle of the cone concavely vaulted. The 

 large sheaths envelop two-thirds or three-fourths of the spines, 

 their sheaths 01 to 015 ; basal breadth of the latter 0'04, distal breadth 012. 



Habitat. Central Pacific, Station 272, surface. 



Family XLIV. DIPLOCONIDA, Haeckel (PI. 140). 



Diji/oconida, Haeckel, 1862, Monogr. d. Radiol., p. 404. 



Definition. ACANTHARIA with simple diplocom'cal shell, composed of two veiy 

 large equatorial spines which are opposite in the hydrotomical axis, are surrounded by 

 conical or cylindrical, often compressed sheaths, and arise from a small central lattice - 



(ZOOL. CHALL. EXP. PART XL. 1885.) Rr 1 1 1 



