R. W. H. ROW—REPORT ON THE SPONGES : NON-CALCARHEA. Bll 
Scattered spicules occur in enormous numbers throughout the sponge, and 
lie without the slightest orientation, either with regard to the sponge itself or 
the spongin-fibres. 
Spicules. (Text-fig. 23.) 
A. Megascleres. (Text-fig. 23, A.) 
The only megascleres are substylostyli. They are rather long, slender 
spicules, with a small and inconspicuous head. They are nearly always 
quite straight, but sometimes slightly and regularly curved. The average 
length is 0°3 mm. in the full-grown specimens, but many may be met with 
much shorter than this. The greatest diameter of the shaft is near its 
middle point, from which spot it tapers gradually towards the head at 
one end and to a sharp point at the other. The diameter of the spicule 
varies from 0-002 mm. to 0°0025 mm. at its widest point; the diameter of 
the head is usually 0°0025 mm. A few specimens can be found sharply 
pointed at each end, but these are probably immature specimens. 
B. Microscleres. (Text-fig. 23, B.) 
The only microscleres met with in this species are toxa. They are 
extremely rare, and only a very few have been seen. They are very delicate 
throughout their length, but strongly bowed at the centre. The length is 
0-2 mm. on the average, and the diameter less than 0:0005 mm. 
Locality. “ Dredged in 9 fathoms from a bottom of coarse sand with shells 
and coral, immediately off the south-east corner of We Shubuk.” 
Distribution. Red Sea. 
OPHLITASPONGIA (?) DIGITIFORMIS, n. sp. (PI. 87. figs. 14, 15.) 
There occur in the collection two specimens of this rather striking species. 
One of these specimens is complete, but the other consists merely of a single 
long cylindrical process, apparently broken off from a large specimen. Both 
the specimens were obtained at the same time. 
The large specimen stands erect on a small oval base, which measures 
39 mm. by 25mm. The basal portion of the sponge is undivided, and is in 
the form of a somewhat oval cylinder, about 80 mm. high and 65 mm. in 
breadth at its widest point. From front to back the diameter of the cylinder 
never exceeds 30 mm. 
From the top of this basal portion arise three large digitiform processes, 
of perfectly uniform diameter throughout their length, which stand upright 
side by side. In section these processes are circular, and two of them 
measure 28 mm. each in diameter ; the third, which is smaller, only measures 
15 mm. in diameter. The two large processes measure 230 mm. in length 
from base to summit. These processes do not branch, in the ordinary sense 
of the term, but from a swelling on the side of one of the large processes 
LINN. JOURN.—ZOOLOGY, VOL. XXXI. 28 
