202 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
it may even reach to two and a half times as long. These elongated rays do 
not lie in any special direction, but point towards any part of the sponge 
indiscriminately, two adjacent spicules frequently having their elongated rays 
pointing in opposite directions. The shorter of the two paired rays is of 
about the same length as the paired rays of the prochiacts. Both the paired 
rays are strongly curved, and are somewhat abruptly pointed. The basal ray 
is quite straight and tapers almost uniformly from base to apex, the tapering 
being slightly more rapid towards the point. 
Gi.) Oxea (Text-fig. 3,¢).—There are present radially arranged oxea, 
extending completely through the sponge-wall and with the distal third of 
their length projecting from the surface of the sponge. They are slightly 
curved, and thickest about one-third of their length from the inner (gastral) ena, 
which is abruptly pointed. The distal end, towards which the spicule 
gradually tapers, is swollen into a head, whose proximal part is barbed on one 
side and rounded on the other. The distal end of the head is pointed. 
C. Gastral cortex (Text-fig. 3, a). 
The gastral cortex is extremely thin, and, like the dermal cortex, contains 
triradiates only of subregular shape. All the rays are equal in length, but 
there can always be distinguished two oral rays and a basal ray by the 
inequality of the angles. Some of the spicules have the paired rays quite 
straight, with the oral angle slightly larger than the paired angles, while in 
others the paired rays at their point of origin lie almost in one straight line, 
with an oral angle of nearly 180°, afterwards bending considerably so as to. 
make the angles between the distal parts of the rays nearly equal. All the 
rays taper gradually from base to apex. 
Spicular measurements (in mm.). 
Basal ray. | Oral rays. Diameter. 
| 
Dermal triradiates .......... 0:27 to , 0:80 0:03 to 0:035 
Subdermal and subgastral do. ..| 0°32 to 0°35 |(a) 0:2 to 0°38 (4) O'1 to 0:12) 0:03 
JEROME) Ga doGdy ab bones od. 0-4 to 0-45 | 0-1 to 0:12 0:025 to 0:03 | 
Gastral cortical triradiates .... O18 to 0:24 0-015 to 0-018: 
| 
OXCR Te ature get ee nr 1:0 to 11 0:03 to 0:04 
A single specimen of this species was obtained at Suez. 
Distribution. Red Sea. 
This species has been placed in the genus Grantilla with the previous species 
owing to the striking similarity between their tubar skeletons, although no 
quadriradiates occur in this species. 
