Tubella vesparioides, Annandale, Rec. Ind. Mus. ii, p. 157 (1908).
Sponge forming rather thick sheets of considerable size, hard but brittle, almost black in colour; oscula inconspicuous; external membrane supported on a reticulate horizontal skeleton.
Skeleton. The surface covered with a network of stout spicule-fibres, the interstices of which are more or less deeply sunk, with sharp fibres projecting vertically upwards at the nodes; the whole mass pervaded by a similar network, which is composed of a considerable number of spicules lying parallel to one another, overlapping at the ends and bound together by a profuse secretion of spongin.
Fig. 25.—Spicules of Tubella vesparioides (from type specimen). × 240.
Spicules. Skeleton-spicules slender, smooth, amphioxous, bent in a wide arc or, not infrequently, at an angle. No true flesh-spicules. Gemmule-spicules terminating above in a rounded, knob-like structure and below in a relatively broad, flat rotula, which is very deeply and irregularly indented round the edge when mature, the spicules at an earlier stage of development having the form of a sharp pin with a round head; shaft of adult spicules projecting slightly below the rotula, long, slender, generally armed with a few stout conical spines, which stand out at right angles to it.
Gemmules numerous throughout the sponge, spherical, provided with a short, straight foraminal tubule, surrounded by one row of spicules, which are embedded in a rather thin granular coat.
| Average length of skeleton-spicule | 0.316 mm. |
| Average breadth of skeleton-spicule | 0.0135 mm. |
| Average length of gemmule-spicule | 0.046 mm. |
| Average diameter of rotula | 0.0162 mm. |
| Average diameter of gemmule | 0.446 mm. |
This sponge is closely related to Tubella vesparium (v. Martens) from Borneo, from which it may be distinguished by its smooth skeleton-spicules and the deeply indented disk of its gemmule-spicules. The skeleton-fibres are also rather less stout. By the kindness of Dr. Weltner, I have been able to compare types of the two species.
Type in the Indian Museum.