8. Zygocircus dodecanthus, n. sp.
Gate semicircular. Ring semicircular or irregularly hexagonal, without edges, with twelve short blunt spines, arising in pairs from the six corners; two apical, two basal, and between them two equatorial corners. Three pairs of spines remain on the straight dorsal rod, three on the curved ventral rod.
Dimensions.—Diameter of the gate 0.04 to 0.06; length of the spines 0.01 to 0.02.
Habitat.—Central Pacific, Stations 263 to 268; depth 2650 to 2900 fathoms.
9. Zygocircus acacia, n. sp. (Pl. [81], fig. 5).
Gate obliquely ovate. Ring semi-ovate, with straight dorsal and curved ventral rod, partly with distorted edges. Six bunches of numerous short and straight conical spines arise from the ring, one larger bunch (often trifid) from the apex, two smaller bunches from the dorsal, two from the ventral rod, and one very large bunch from the base. The six bunches are often more separated, smaller, and the spines shorter than in the figured specimen, which passes over into Dendrocircus.
Dimensions.—Diameter of the gate 0.12 to 0.16; length of the spines, 0.01 to 0.07.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
10. Zygocircus polygonus, n. sp. (Pl. [81], fig. 2).
Gate irregularly roundish or ovate. Ring irregularly polygonal or sometimes nearly circular, without edges, armed with a single series of ten to fifteen short pyramidal spines, which are irregularly disposed in the sagittal plane. The ventral rod is strongly curved, often semicircular, the dorsal rod less curved or nearly straight.