Gellius aculeatus, sp. nov.
(Plate xviii., fig. 3).

Sponge incrusting (attached to a piece of coral), measuring 45 mm. by 20 mm., and from 5 to 12 mm. in thickness.

Surface very uneven possessing numerous compressed promi-nences, from 4 to 7 mm. in height, 05 to 0·8 mm. in their broad diameter, and from 1 to 3 mm. apart, proximally the processes are connected by narrow ridges, distally they taper to acute points; they are more or less compressed throughout their length, rarely rounded.

Dermal membrane, thin, smooth and somewhat opaque, pores not visible, oscula few, scattered, occurring between the aculeate pro-cesses, subcircular in shape and from l·2 to 1·5 mm. in diameter.

Texture soft, compressible, moderately tough.

Colour in spirit dirty cream.

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The skeleton consists of large strongylote spicules, which run more or less vertically from the base to the surface, either singly or in twos or threes, as they approach the surface they converge, forming whisp-like bands from O·l to0·2 mm. wide; at the surface they form the main support of the aculeations.

In addition to the large strongyla there are numerous small oxeote spicules irregularly distributed throughout the body of the sponge; they are scarce or absent from the dermal membrane, and from the aculeate processes. Sigmata of about one and a half turns are abundant and evenly distributed in the dermal membrane, internally they appear to be confined to definite tracts.

Megasclera—(a) Straight, elongate, round ended strongyla gradually tapering from the centre to the extremities.

Size—About 1·6 by 0·02 mm.

(b) Oxea, small, slender, straight, tapering gradually at each end to acute points.

Size—About 0·14 by 0·0035 mm.

Microsclera—Very slender sigmata of about one and a half turns; length about 0·02 mm.

Deep water in the lagoon.

This species is allied to Gellius carduus in outward form, the spicules are, however, very much larger than in that species.

Clathria pellicula, sp. nov.

Sponge incrusting, from 1 to 1·5 mm. in thickness; surface minutely conulose, with numerous pores in groups of from four to six. Oscula scattered, circular, about 0·25 mm. in diameter.

Colour in spirits yellowish-gray.

Skeleton columnar, consisting of whisp-like multispicular fibres, with little or no spongin; they are made up of irregularly dis-posed smooth styli or subtylostyli and accompanied by spined styli; there are but few spicules between the fibres. The dermal skeleton consists of rather distant radiating tufts of smooth styli.

Megasclera—(a) Smooth styli or subtylostyli of the fibres, gradually sharp pointed, the slightly enlarged basal extremities of the larger spicules often minutely spinose.

Size—About 0·23 by 0·0042 mm.

(b) Smooth slender styli or subtylostyli of the dermal tufts.

Size—Variable from 0·25 to 0·4 by 00035 mm.

(c) Echinating styli, straight, gradually tapering to sharp points, spines irregularly disposed, strong, and recurved, the apical fourth of the spicule almost smooth.

Size—0·1 by 0·008 mm.

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Microsclera—(a) Minute slender isochelæ; length about 0·15 mm.

(b) Long slender toxa, with a short slight bend in the middle, straight limbs, and smooth acute points; length 0·35 mm.

This species forms a thin skin-like covering over an oyster shell, Ostrcea crista-galli, Linn.

Obtained in the lagoon in eighteen fathoms of water.

Agelas gracilis, sp. nov. (Plate xviii., fig. 4).

Sponge subcylindrical, unbranched, attached to fragments of shells. There are four pieces, three of which take the form of simple filaments measuring from 2 to 3 mm. in diameter, and from 25 to 75 mm. in length. The fourth example consists of six or seven processes arising from an expanded base; at their origin and for about half their length they are somewhat irregular, a little flattened and joined together at various points, giving the basal portion a clathrous aspect. The upper half terminates in a series of subcylindrical filaments from 5 to 25 mm. in height and 2 mm. in diameter, which taper gradually to the extremities.

The texture is spongy and soft, but pretty tough. Colour in spirits grayish-yellow. The surface is uneven, hispid, beset with numerous minute conuli from 0·2 to 0·5 mm. high and 2 to 5 mm. apart. A few minute pores are visible between the conuli.

The skeleton is reticulate, the stout primary fibres forming an axial plexus from which secondary and connecting fibres are given off. The mesh is oblong or oval, rarely angular. The primary fibres measure 0·07 mm., the secondaries 0·045 mm., and the connecting fibres 0·025 mm.

The echinating spicules situated on the main fibres are numerous and generally more or less parallel with them, on the more slender fibres they are usually at right angles to their support.

Megasclera—Of one kind only, consisting of straight or but little curved, verticillately spined styli, from the truncated base they taper gradually to sharp points. The verticils vary in number from 16 to 24, according to the size of the spicule. The first three or four are closer than the rest, and consist of prominent straight spines, towards the apex the spines are recurved.

Size—Variable from 0·1 to 0·22 mm. by 0·007 to 0013 mm. The verticils are about 0·01 mm. apart.

Obtained by tangles, associated with Gorgonice, in forty to seventy fathoms, on the western slope of the atoll.

Echinodictium asperum, Ridley & Dendy.

Echinodictium asperum, Ridley & Dendy, Chall. Rep. Zool., xx., p. 165, pl. xxxii., fig. 2.

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Of this well marked species there are two examples, one dry the other in spirit. The dried example measures 170 mm. by 120 mm., and 100 mm. in height. The one in spirit measures 120 mm. by 95 mm., and 90 mm. in height. They are thus larger than those obtained by the Challenger Expedition.

The spined styli are smaller than those of the type, they seldom exceed 0·12 in length.

Colour in spirit, gray.

Dredged in the lagoon in company with Laganum and Maretia.