Definition.—Rings of the disk partly concentric, completely annular; partly spiral or interrupted, often irregular.
8. Stylodictya perispira, n. sp.
Inner rings of the disk (two to four) concentric, circular, or roundish, outer rings forming a simple spiral, breadth a little increasing from the centre. Pores subregular, circular, about two on the breadth of each ring. Marginal spines bristle-shaped, ten to fifteen, about as long as the diameter of the disk.
Dimensions.—Diameter of the disk (with eight rings) 0.2; breadth of each ring 0.013; pores 0.004.
Habitat.—Pacific, central area, Station 272, depth 2600 fathoms.
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. Radial beams partly interrupted, partly piercing. Marginal spines fifty to eighty, very variable in size and number, 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 the 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 setigera, Ehrenberg.