Page:Scientific results HMS Challenger vol 18 part 1.djvu/773

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Definition.— with a simple, spherical or lenticular, central chamber, surrounded by three simple arm-chambers. Notches between the three arms transformed into gates by a connecting equatorial girdle.

The genus Triopyle differs from the preceding Triolene in the development of a simple ring or latticed equatorial girdle, which connects the distal ends of the three arm-chambers, and transforms the open notches between them into three gates. The ring may be circular, triangular, or hexagonal.

1. Triopyle circulus, n. sp.

Disk circular, three times as broad as the hexagonal central chamber. Three arm-chambers trapezoidal, at the convex distal end as broad, at the base half as broad as the three circular gates between them. Surface smooth. No marginal spines on the girdle.

Dimensions.—Diameter of the disk 0.045, of the gates 0.015.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Triopyle hexagona, n. sp. (Pl. 48, fig. 13).

Disk hexagonal, three times as broad as the circular central chamber. Three arm-chambers trapezoidal, at the truncated distal end as broad, at the base half as broad as the three triangular gates between them. Surface smooth. No marginal spines.

Dimensions.—Diameter of the disk 0.05, of the gates 0.02.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

3. Triopyle trigona, n. sp.

Disk triangular, four times as broad as the circular central chamber. Three arm-chambers nearly triangular, at the narrow base half as broad, at the distal end twice as broad as the circular or roundish gates. Surface smooth. On the margin (in the equatorial plane) three strong pyramidal spines (at the end of the arms).

Dimensions.—Diameter of the disk 0.04, of the gates 0.015.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

4. Triopyle cordigera, n. sp.

Disk hexagonal, four times as broad as the hexagonal central chamber. Three arm-chambers triangular, at the base half as broad as at the truncated distal end, about the same size as the