316 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
RENIERA TABERNACULA, n. sp. (Text-fig. 9.) 
This species is represented by a single, apparently complete specimen of 
nearly triangular shape. The sponge measures 59 mm. in its greatest length 
and is 22 mm. wide. It is flattened and, in fact, nearly lamellar, being only 
7-8 mm. in thickness. The specimen is quite unattached to any support, but 
on one of the two triangular surfaces (presumably the lower) there is a deep 
oval hollow, extending almost through the whole thickness of the sponge, 
from which the original support of the sponge has presumably been detached. 
From the shape of the cavity this support seeras to have very possibly been a 
crab. 
The surface of the sponge is devoid of fistulee or outgrowths, but never- 
theless it is not quite smooth, owing to the projection of the ends of the 
spicular fibres slightly from it. The dermal membrane is almost entirely 
absent, but the small portion remaining is quite smooth between the projecting 
fibres of spicules, and pierced with very numerous pores. The rest of the 
sponge surface is regularly reticulate, with a number of small holes in each 
mesh. Whether these are oscula or inhalant canals cannot be ascertained, as 
the dermal membrane is absent. 
The colour in spirit is yellowish white. 
The texture of the sponge is tough, but very easily compressible. 
The skeleton is of a typical Renierine type, and possesses a large number 
of very clearly marked main fibres, whose direction is radial and whose ends 
project from the surface of the sponge. Owing to the lamellar character of 
the sponge, however, the radial direction of the fibres has become modified in 
the central parts of the sponge so that they run from the base to the upper 
surface of the sponge, directly perpendicular to both surfaces. These fibres 
are densely spicular, the spicules in them being frequently 6—10-serial ; they 
lie rather irregularly in the sponge, and the distance between them varies 
considerably, especially in the deeper parts of the specimen. At the surface 
they are more regular in arrangement, and the average 
distance between them is 0°15 mm., or rather more than 
the length of the individual spicules. Many of them 
branch, and a very few anastomoses between main fibres 
were observed. 
Connecting fibres, lying tangentially in the sponge, and 
exactly similar to the main fibres in structure and size, 
Fic. 9.— Reniera Occur occasionally, but the greater part of the skeleton 
tabernacula. Spi- network is formed of a regular reticulation of uniserial 
cules, X 235. secondary fibres, which form a rectangular mesh, each 
side of which is composed of a single spicule. 
There is no dermal skeleton distinct from the above-described secondary 
fibres. 
