328 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
At the conuli which cover the surface the reticulation of the fibres becomes 
somewhat closer, and as a rule three or four of the primary fibres come close, 
together, and all take part in forming the support of the conulus. Between 
these main fibres there occurs a dense reticulation of 
the small secondary fibres, and the dermal reticulation 
is also somewhat closer. 
Spicules. (Text-fig. 13.) 
The only spicules which occur in the sponge are oxea. 
They are slender, rather small spicules, which are of the 
same thickness for most of their length, but somewhat 
| gradually pointed at the ends. They are almost always 
quite straight, but a few can be seen slightly curved. 
Fig. 13.—Spinosella in- They average 0°095 mm. to 0:1 mm. in length, and are 
crustans. Spicules, very variable in thickness. Nearly all the spicules are 
ae about 0:001 mm. in diameter, but a few may be found 
as much as 0:0025 mm. thick. 
Locality. The specimen was attached to a dead pearl-shell obtained at 
Khor Dongonab., 
Distribution. Red Sea. 
Sub-Family GELLUN. 
H{aploscleride with diactinal megascleres, and sigmata or toxa or microxea 
for microscleres. 
GELLIODES PocuLUM, Ridley § Dendy. Var. 
Synonymy :— 
1887. Gelliodes poculum, Ridley & Dendy (24). 
Two specimens of this species occur in the collection—one fairly large and 
apparently complete, the other a mere fragment. The larger is small 
compared with the ‘Challenger’ species, and differs slightly from the type 
there illustrated. It consists of an irregularly ramifying tubular basal mass, 
from which arise a number of upright hollow tubes. In the basal part there 
occur several horny Lamellibranch shelis (probably Avicula sp.). 
The largest tube is 20 mm. in diameter, and the various tubes which form 
the specimen vary from this size down to 3 mm. in diameter. The canal 
inside the basal portion is usually about 3 mm. in diameter, but may reach as 
muchas 5mm. The upright tubes have comparatively much larger canals 
inside them, and at the summit the wall of the tube is thinned out to a mere 
oscular rim. The oscula at the top of the tubes attain a maximum diameter 
