Acanthella Stipitata, Carter.

Acanthella stipitata, Carter, Ann. and Mag. Nat. Hist., (5), vii., p. 380, pl. xviii., fig. 8; Ridley & Dendy, Chall. Rep. Zool., xx., p. 178; Dendy, Proc. Roy. Soc. Vic., (n.s.) ix., 1896, p. 237.

A small fragment is here somewhat doubtfully referred to this species.

Deep water in the lagoon.

Acanthella pulcherrima,
Ridley & Dendy.

Acanthella pulcherrima, Ridley & Dendy, Chall. Rep. Zool., xx., p. 177, pl. xxxii., fig. 3.

A single specimen of this species is in the collection.

Associated with the preceeding.

Ciocalypta Incrustans, sp. nov.
(Plate xviii., fig. 2).

Sponge incrusting, forming large flat expansions of a fairly uniform thickness. There are several pieces, the largest is 55 mm. by 45 mm., and 10 mm. in thickness.

Colour in formol yellowish-white.

Texture soft and fragile, readily breaking by its own weight if handled.

Surface minutely conulose; the conuli are from 1 to 1·5 mm. apart, and from 0·5 to 1 mm. in height.

The dermal membrane is thin and transparent, with numerous inhalent pores which are situated in the depressions between the conuli. Oscula scattered about 2·5 mm. in diameter, with slightly raised margins.

Skeleton.—The main skeleton consists of columns of spiculo-fibre without much obvious spongin. The columns run vertically from the base to the surface where they terminate and form the support of the dermal membrane. The columns are from 0·3 to 0·6 mm. in diameter, they are separated by spaces 0·4 to 0·6 mm. wide.

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The fibres are pretty uniform in diameter without any well defined branches. Occasionally they appear to be connected by a somewhat dense bundle of spicules. The intercolumnar spaces are sparsely spiculate. The spicules are rather irregularly arranged, both in the spaces and the columns. There are no traces of a special basal or dermal layer of spicules.

Megasclera—Of two kinds, stylote and oxeote. (a) The styli are usually curved, rarely straight, often bent a short distance from the well rounded base; they taper gradually from about the middle to sharp points.

Size—Variable, about 0·2 to 0·04 mm. by 0·0095 mm.

(b.) The oxea are not so numerous as the styli, they are usually bent in the middle, and taper gradually to sharp points.

Size—About 0·35 by 0·0075.

Besides the above, there are a number of very slender oxea and styli scattered through the body, probably the young of the larger forms.

Reefs in the lagoon.