Section Scleraxonia.
Family Solerogorgia.
Keroeides gracilis, sp. nov.

(Plate xvi., figs. 1 - 5.)

This species is represented by four fragments, of which the largest is 50 mm. in height, and 30 mm. in breadth, the main stem is 2 mm. in diameter. Near the base it bears four simple branches, which are alternate, in one plane, and at very unequal distances apart; the largest branch is 30 mm. in length and 1 mm. in diameter.

The polyps are small and roundly conical in shape, from 4 to 6 mm. in height, 1 mm. in diameter at the base, and ·6 to ·8 mm. at the summit, they are placed on the sides of the stem and branches alternately, those on the latter are inclined towards one side of the plane of branching, their apertures being visible from the front only.

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The cœnenchyma is thin, smooth, without external grooves, and densely charged with large closely tuberculate spindles.

The axis consists of a series of long spicules firmly cemented together, its diameter near the base is ·9 mm., the terminal twigs ·1 mm.

The spicules of the cœnenchyma are straight or but little curved spindles, closely beset with either simple or compound tubercles. On and in the neighbourhood of the verrucae they are very irregular in shape, placed transversely and frequently adapted to each other, having one or both ends obliquely truncated, and including such forms as the following: elongate triangles, clubs, boomerangs and short bent spindles. By transmitted light they are of a bright brick red colour.

The retracted polyps are covered by a series of short, straight, or curved spiny spindles, of a pale pink or white colour; there are a number of spicules embedded in the tentacles, which have a few blunt spines and acutely-pointed ends.

The spicules are as follows:—

The colour is bright coral-red, the polyps are yellowish-white.

This species differs from Keroeides koreni in its erect non-pendulous habit and in the characters of its spicules.