Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, First Part: Porulosa (Spumellaria and Acantharia) / Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII

by Ernst Haeckel

Dimensions.—Radius of the anterior arms 0.4, of the posterior 0.2; longitudinal constriction 0.3, transverse 0.2.

Habitat.—North Pacific, Station 248, surface.

3. Myelastrum heteropterum, n. sp. (Pl. [47], fig. 8).

Anterior arms trifid, about as long as broad, with two incisions at their broad truncated end. Posterior arms about half as large, simple, with rounded blunt ends. Sagittal constriction two-thirds as large as the transverse. Surface bristly.

Dimensions.—Radius of the anterior arms 0.65, of the posterior 0.035; longitudinal constriction 0.4, transverse 0.6.

Habitat.—South Pacific, Station 291, surface.

Subgenus 2. Myelastromma, Haeckel.

Definition.—All four arms (posterior as well as anterior) lobated or cleft.

4. Myelastrum octocorne, n. sp. (Pl. [47], fig. 12).

All four arms with a deep incision in their distal half; anterior arms broader, but shorter than the posterior; in the anterior arms the two lobes are of the same size, in the posterior arms the median lobe is longer than the lateral lobe. Sagittal constriction little smaller than the transverse. Surface of the disk rough.