Taf. xiii. figs. 1-3 (not 4) and Taf. xxxii. fig. 1 (not 2 and 3). Cœlodendrum has been derived from Cœlodoras by furcation and repeated dichotomous ramification of the hollow radial tubes which arise from the galea.
Subgenus 1. Cœlodendridium, Haeckel.
Definition.—Ramification of the hollow tubes regularly dichotomous, each branch being forked again; therefore the two terminal ramules of the last branches equal.
1. Cœlodendrum ramosissimum, Haeckel.
Terminal branches regularly forked, with two equal, smooth, nearly straight or slightly curved fork-branches, diverging at right angles; their end-knobs with four crossed (or sometimes five or six) short recurved teeth.
Dimensions.—Diameter of the spherical skeleton 1.2 to 1.8, of the two central valves 0.2 to 0.25.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; many Stations, surface and at various depths.
2. Cœlodendrum spinosissimum, n. sp. (Pl. 121, fig. 7).
Terminal branches regularly forked, with two equal, smooth, straight, fork-branches, diverging at right angles, their end-knobs echinoidal, subspherical or club-shaped, with numerous short radial thorns.
Dimensions.—Diameter of the skeleton 2 to 2.2, of the two central valves 0.25 to 0.03.
Habitat.—Tropical Atlantic, Stations 346 to 349, surface.
3. Cœlodendrum furcatissimum, n. sp. (Pl. 121, fig. 1-4).
Terminal branches regularly forked, with two equal, smooth, straight, or slightly curved fork-branches, diverging at acute angles; their end-knobs very small, with three short, diverging, conical teeth.
Dimensions.—Diameter of the skeleton 2 to 2.5, of the two central valves 0.3 to 0.4.
Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; many Stations, surface, and at various depths.
4. Cœlodendrum bifurcum, n. sp.
Terminal branches regularly forked, with two equal, smooth, more or less curved fork-branches, diverging at acute angles; their end-knobs thin, with two slender, parallel, bristle-shaped teeth.
Dimensions.—Diameter of the skeleton 0.6 to 0.8, of the two central valves 0.1 to 0.15.
Habitat.—North Pacific, Stations 252 to 256, surface.
