356 MARINE BIOLOGY OF THE SUDANESE RED SBA. 
1:0 mm. in diameter, asarule. They occur scattered in considerable numbers: 
over the whole surface. 
The pores are very small, irregularly scattered over the 
surface, but not grouped into special pore-areas. 
The colour of the sponge in spirit is a dark grey-brown. 
The texture is very lax and the whole sponge very easily 
damaged. 
Skeleton arrangement. 
The skeleton consists of spicular fibres very irregularly 
arranged, and lying quite unoriented in the sponge. Asa 
rule, these fibres contain only five or six rows of spicules, 
but here and there they form dense spicule-bands, which 
may contain as many as 50 or even more rows of spicules. 
There is no special dermal skeleton. 
Spicules. (Text-fig. 25.) 
The only spicules occurring in the sponge are tylostyles, 
Fig, 25. with well-developed heads. They average 0:02 mm. in 
Hymeniacidon length and 0:0025 mm. in diameter. The head measures 
sosterce. 0:004 mm. in diameter. 
Spicules, x 350. 
Locality. Mersa Wadi Lehami, Egyptian coast. 
Distribution. Red Sea. 
ACANTHELLA AURANTIACA, Keller. 
Synonymy :— 
1891. Acanthella aurantiaca, Keller (18). 
1904. Acanthella aurantiaca, Dendy (11). 
A single specimen of this species is preserved in the collection. It 
consists of three or four irregular lamelle, growing adjacent to each other 
and attached by their contiguous surfaces to each other at frequent intervals. 
It is thus somewhat difficult to distinguish the various lamellee from each 
other. 
The sponge is 80 mm. high and 50 mm. wide. The lamelle vary in 
thickness from 3 mm. to 5 mm. | 
The skeleton arrangement and the measurements of the spicules are exactly 
similar to Keller’s description. 
Locality. ‘From shallow water of the inner parts of Suakin Harbour, 
particularly the cove north-west of Condenser Island.” 
Distribution. Red Sea, Ceylon. 
