358 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
level of the surface, but sufficiently marked to prevent its appearing smooth. 
The photograph gives a very definite indication of this appearance. 
The pores are difficult to see, but appear to be irregularly scattered all 
over the sponge surface, and not in pore-areas. 
The colour of the specimen is dark brown. 
The texture is very firm and tough, almost hard. The sponge is not at all 
easy to cut, and difficult to bend out of shape. 
Skeleton arrangement. (PI. 89. fig. 21.) 
The main skeleton consists of a large number of spicules not arranged in 
bundles, but all definitely oriented in the sponge. ‘he direction in which 
the spicules lie is an obliquely radial one, partially pointing towards the 
side of the sponge lamella, and partly towards its edge. As the spicules 
approach the surface they become more and more nearly perpendicular to it, 
but as a rule never actually attain to the completely vertical position. 
At the surface of the sponge there occur bundles of spicules, arranged at 
intervals of 0-2 mm. to 0°5 mm., instead of the 
scattered spicules of the general skeleton. These 
i bundles vary ‘considerably in ‘size, and may 
contain any number of spicules from 6 or 8 to 20. 
The ends of the fibres project slightly from the 
surface and render it minutely hispid. 
Spicules. (Text-fig. 26.) 
The only spicules which occur in the sponge are 
styli. They vary very considerably in size and 
shape, from straight to strongly curved, and from 
0-2 mm. to0°35 mm.in length. An average length 
is about 0°3 mm. Their greatest diameter occurs 
near the rounded end, from which point they taper 
| very gradually indeed for the major portion of their 
| | length and more rapidly in the last part. The 
| actual end is usually irregular, and frequently 
possesses the typical Axinellid end. The diameter 
of the largest specimens does not exceed 0:008 mm., 
and most are not more than 0:005 mm. 
Fig. 26.—Phakellia palmata. ; ? 
Spicules, x 250. Locality. The specimen occurred in the bottle 
with macerated labels, with Phakellia donnani. 
It is therefore uncertain where the sponge was obtained, but it was possibly 
off Cape Hlba. (For the reasons for assigning this locality to the specimen, 
see Phakellia donnani, p. 357.) 
Distribution. Red Sea. 
