Acanthostaurus forceps, Haeckel, 1862, Monogr. d. Radiol., p. 396, Taf. xix. figs. 3, 4.
Acanthometra forceps, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 809.
Spines pincer-shaped, linear, compressed, cleft nearly throughout their whole length into two parallel thin, straight branches, which are united only at the pyramidal base and by means of a small bridge in the middle part. Four main spines twice as long and as broad as the sixteen others. Central capsule square, filled up with red pigment, and containing yellow bodies. The diagonals of the square are the two equatorial axes.
Dimensions.—Length of the four main spines 0.1, of the sixteen others 0.05; breadth of the former 0.01, of the latter 0.005.
Habitat.—Mediterranean (Messina); North Atlantic, Canary Islands, Station 354, surface.
7. Acanthostaurus hastatus, Haeckel.
Acanthostaurus hastatus, Haeckel, 1862, Monogr. d. Radiol., p. 397, Taf. xix. fig. 5.
Acanthometra hastata, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 809.
Spines of very different size and form; four equatorial spines cylindrical in the basal half, spear-shaped or lanceolate in the distal half, with thin edges, little longer, but five to eight times as broad as the sixteen smaller spines, which are cylindrical, of equal breadth throughout their whole length, with bifid apex. Base of all twenty spines pyramidal, without leaf-cross. Central capsule yellow, spherical, or lenticular.
Dimensions.—Length of the four major spines 0.066, breadth in the middle 0.005, on the apex 0.008; length of the sixteen smaller spines 0.054, breadth 0.001.