324 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
Spicules. (Text-fig. 12.) 
) 
| The spicules of this species consist solely of oxea, which 
are nearly always curved, cylindrical oxea, tapering from 
the middle to either end. The ends are sharply pointed. 
The average length of the spicules is 0:09 mm. 
| Spongin. 
: . The spongin coating the spicules is very pale in colour 
Fie. 12.— Chalina © x 
lol at Pa 6 ~~ © 7 a 
ap. Scnles. and not very abundant in the main fibr es. In actual size 
x 400. the secondary fibres sometimes quite equal the primary 
fibres, though they contain many less spicules. 
Locality. From Suakin Harbour, in 5 fathoms of water. 
Distribution. Red Sea, 
CERAOCHALINA DENSA, Keller. 
Synonymy :— 
1889. Ceraochalina densa, Keller (18). 
Two specimens occur in the collection belonging to this species ; they are 
large spreading sponges, not rising very high from their support, and they bear 
a number of large, low tubes, partially fused together where their sides come 
in contact, which form the major portion of the specimens. These tubes are 
about 25 mm. high from base to summit, and 60 mm. in diameter in the 
largest specimens. The whole sponge forms a low cushion. 
The skeleton, both in structure and measurements, and the spicules occurring 
in it, agree very closely with Keller’s descriptions. 
Locality. Suakin Harbour. 
Distribution. Red Sea. 
SIPHONOCHALINA CONICA (Keller). 
Synonymy :— 
1889. Phylosiphonia conica, Keller (18). 
Several specimens of this species occur in the collection. The largest 
forms an irregular spreading mass covering a large base, with several tubular 
processes arising from it. Another specimen is growing over a group of 
mussels, and others have mussels embedded in them. In all a very great 
similarity of form is apparent, and the tubular processes which arise from 
them are very similar. From the largest specimen 12 of these tubes arise, 
which are 15 mm. high and 8 mm. in diameter at the base. At the summit 
the diameter of the tube is only 6 mm., and here the sponge-wall merely 
consists of the oscular lip, the osculum being as wide as the tube itself in this 
