2. Pleuraspis amphithecta, n. sp.
Radial spines two-edged, leaf-shaped, strongly compressed, pointed at both ends; outer half longer than the inner. Two apophyses of each spine simply forked, with short and very broad branches; condyles not thickened. Forty sutures, broad. Twenty-two large meshes twice to three times as broad as the bars. By-spines zigzag, half as long as the radius. (Resembles Phractaspis complanata, Pl. [137], fig. 1.)
Dimensions.—Diameter of the shell 0.12, of the meshes 0.02 to 0.03; bars 0.012.
Habitat.—Central Pacific, Station 274, surface.
3. Pleuraspis costata, Haeckel.
Acanthometra costata, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 49, Taf. ii. fig. 1, Taf. x. figs. 4-6.
Dorataspis costata, Haeckel, 1862, Monogr. d. Radiol., p. 414, Taf. xxiii. fig. 1.
Radial spines roundish, conical, pointed at both ends; outer and inner halves of nearly equal length. Two apophyses of each spine simply forked, with broad branches and thickened condyles. Forty sutures, broad. Twenty-two large meshes, four to five times as broad as the bars. By-spines straight, denticulate, half as long as the radius. (This common species is rather variable in size and details.)
Dimensions.—Diameter of the shell 0.1 to 0.13, meshes 0.03 to 0.06, bars 0.005 to 0.01.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.