380 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
in section, and are tubular, each bearing an osculum at the summit ; they 
vary in diameter from 8 mm. to 35 mm. 
The surface of the sponge is minutely and regularly conulose, the conuli 
varying in height from 0:1 mm. to 0°5 mm. ; they are on the average about 
1:0 mm. apart. 
The oscula are not confined to the cones referred to above, but occur 
sparsely scattered over the whole of the sponge-surface. There are four or 
five of these oscula on each specimen, and they measure about 3 mm. to 
4 mm. in diameter. 
The pores were very difficult to make out, but where seen they were 
numerous and scattered over the whole surface. 
The colour of the sponge in spirit is very deep black on the outside and a 
dark brownish in the interior. 
The texture is very soft and delicate, but also very firm. 
Skeleton arrangement. 
The main fibres run radially, and contain foreign bodies; they measure 
0:08 mm. in diameter. The secondary fibres are not definitely oriented, but 
the reticulation is fairly regular and even. The diameter of these secondary 
fibres does not exceed 0°02 mm. ‘The diameter of the mesh is about 0°1 mm. 
The canal-system needs no special description, there being no points in 
which the present specimens differ from the descriptions previously given of 
this variety. 
Locality. Suakin Harbour. 
Distribution. Red Sea. 
EUSPONGIA OFFICINALIS, var. CEYLONENSIS. 
Synonymy :— 
Euspongia officinalis, var. ceylonensis, Dendy (11). 
This sponge is represented in the collection by a fairly large and extremely 
fine specimen. It consists of a subspherical cushion attached to the sub- 
stratum by a broad base, and perfectly regular in shape. The surface is 
very finely conulose, and the conuli are very small and close together ; they 
are mostly about 0°2 mm, high. 
The oscula are large, but not numerous, and scattered regularly over the 
surface. They measure 3 mm. to 9 mm. in diameter. 
The colour of the specimen is black in spirit. 
The skeleton consists of a reticulation of spongin-fibre, in which primary 
and secondary fibres can be clearly differentiated. The main fibres measure, as 
a rule, 0°15 mm. in diameter, and are filled with extremely small sand-grains. 
They run strictly radially, and are very regularly distributed throughout 
the sponge, usually being separated at the sponge surface by about 0°8 mm. 
