median lobe is longer than the lateral lobe. Sagittal constriction little smaller than the transverse. Surface of the disk rough.
Dimensions.—Radius of the anterior arms 0.45, of the posterior 0.62; longitudinal constriction 0.25, transverse 0.3.
Habitat.—Pacific, central area, Station 271, surface.
5. Myelastrum farfalla, n. sp. (Pl. 47, fig. 10).
All four arms with a shallow incision at their distal end. Anterior arms broader, but shorter than the posterior; in each arm the anterior lobe is shorter than the posterior. Sagittal constriction smaller than the transverse. Surface smooth.
Dimensions.—Radius of the anterior arms 0.4, of the posterior 0.6; longitudinal constriction 0.5, transversal stricture 0.6.
Habitat.—Pacific, central area, Station 274, surface.
6. Myelastrum papilio, n. sp. (Pl. 47, fig. 6).
All four arms with a shallow incision at their distal end. Anterior arms triangular, of the same breadth, but of the double length of the square posterior arms. Sagittal and transverse constrictions of the same length. Surface ciliated. (Resembles a butterfly.)
Dimensions.—Radius of the anterior arms 0.7, of the posterior 0.4; longitudinal and transverse constrictions 0.4.
Habitat.—North Pacific, near Japan, Station 241, surface.
7. Myelastrum decaceros, n. sp. (Pl. 47, fig. 7).
Anterior arms bifid, with one shallow incision at their distal end. Posterior arms of the same length, but much broader, trifid, with two incisions (one larger and one smaller). Sagittal and transverse constrictions of the same length. Surface spiny.
Dimensions.—Radius of all four arms 0.4; longitudinal and transverse constrictions 0.35.
Habitat.—Pacific, central area, Station 272, surface.
8. Myelastrum dodecaceros, n. sp. (Pl. 47, figs. 11, 11a).
Anterior arms trifid, with two shallow incisions at their distal end. Posterior arms about one-third larger, also trifid, with one deeper anterior and one shallower posterior incision. Sagittal constriction much longer than the transverse. Surface ciliated, covered with numerous thin and long radial bristles (fig. 11a).
Dimensions.—Radius of the anterior arms 0.5, of the posterior 0.7; longitudinal constriction 0.5, transverse 0.35.
Habitat.—Pacific, central area, Station 270, surface.
