REPORT ON THE RADIOLARIA. 877 



2. Hexaconus coronatus., u. sp. (PI. 139, fig. 5). 



All six hydrotomical spines of e.qual size, conical, somewhat compressed, with two prominent 

 edges, scarcely as long as the radius of the shell. Sheaths crested, strongly dentated on the mouth, 

 three times as hroad as long and only one-sixth as long as the spines. Fourteen smaller spines 

 about half as large as the six principal spines, of the same form, but without coronated sheaths. 



Dimensions. — Diameter of the shell 0-2 ; length of the six hydrotomical spines 01 ; basal 

 breadth 002. 



Habitat. — North Pacific, Station 253, surface. 



3. Hexaconus velatus, n. sp. (PI. 139, fig. 6). 



All six hydrotomical spines of equal size, conical, somewhat compressed, shorter than the radius 

 of the shell. Sheaths very large, truncated conical, enveloping the spines almost entirely, with 

 crested wall, only half as broad at the constricted mouth as at the base. The fourteen smaller spines 

 about half as large as the six principal spines, of the same form, but without large sheaths. 



Dimensions. — -Diameter of the shell 0'12 ; length of the .six hydrotomical spines 0"05 ; basal 

 breadth 0-01. 



Habitat. — North Atlantic, Station 354, surface. 



Subgenus 2. Hexaconidium, Haeckel. 



Definition. — Six liydrotomical spines of unequal size, two opposite (equatorial) much 

 larger than the four other (polar) spines. 



4. Hexaconus serratus, n. sp. (PI. 139, fig. 4). 



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

 shell and one and a half times as large as the four polar ; all of the same form, triangular, com- 

 pi-essed, with six prominent edges. Sheaths cylindrical, half as long as the spines, with prominent 

 crests, and with strong serrated teeth at the distal mouth. The fourteen smaller spines scarcely 

 one-fourth or one-sixth as large as the six principal spines, without prominent sheaths. 



Dimensions. — Diameter of the .shell 0-2 ; length of the equatorial spines O'l, basal breadth 

 0-05 ; length and breadth of the .sheaths 0'05. 



Habitat. — South Pacific, Station 288, surface. 



5. Hexaconus vaginatus, n. sp. (PI. 139, fig. 7). 



Six hydrotomical spines of unequal size ; the two equatorial very stout, pyramidal, six-edged, 

 nearly as long as the diameter of the shell, and on the base three to four times as broad as the 

 eighteen other spines, which are much thinner, all nearly of equal length, and two-edged. All 



