African Freshwater Sponges. 99 
Each is enclosed in a thick coat of spongin. ‘he gemmule- 
spicules lie tangentially to the surface, and are embedded in 
this coat. The spicules are fairly numerous, but are not 
closely packed together as in the allied species S. zndica, 
Annandale, S. sumatrana, Weber, and S. bombayensis, Carter. 
There is a short foraminal tubule which lies rather to one side 
of the gemmule in its natural position. 
Spicules.—The macroscleres are slightly curved, uniformly 
microspined strongyla. The ends are a little swollen and 
there is often a slight swelling in+the centre of the shaft. 
The strongyla measure 0°13-0°17 mm, in length by 0°01- 
0015 mm, Among them are scattered a few slender smooth 
oxea with a well-marked swelling in the centre of the shaft. 
These are nearly the same length as the preceding spicules, 
and are apparently young forms of the macroscleres, as they 
lead on to thicker spicules which are obviously developing 
macroscleres and which are nearly cylindrical, but some of 
which still retain rather pointed ends. 
The free microscleres are slightly curved, sharply pointed, 
microspined oxea measuring 0:06-0:09 mm. in length by 
0:0025 mm. Some have a very feeble swelling at the centre 
of the shaft. 
The gemmule-spicules are small, curved, sausage-shaped 
spicules uniformly covered with minute spines. Sometimes 
the ends are pointed instead of being rounded off as is usually 
the case. There is often a slight swelling in the centre of the 
shaft. The spicules measure 0:035—-0:06 mm. in length, with 
a maximum diameter of 0°003 mm. 
Locality. Benguela; on a shell of Atherta elliptica, var. 
tubifera. 
The subgenus Stratospongilla, Annandale (1), to which the 
foregoing species belongs, is chiefly tropical in its distribution 
(4). At the present day it is known to be represented in 
India by three species—S. bombayensis, Carter, S. indiea, 
Annandale, and 8. graveleyi, Annandale; it oceurs in Su- 
matra—8. sumatrana, Weber ; in tropical and South Africa 
— 8. rousseleti, Kirkpatrick, S. schubotzi, Weltner, varieties 
of S. sumatrana, Weber, and S. bombayensis, Carter ; in the 
Fiji Islands—S. gilsoni?, Topsent ; and in Wastern China— 
S. sinensis, Annandale. One species—S. clementis, Annan- 
dale—from the Philippines is doubtfully assigned to the 
subgenus, and S. navicella, Carter, from the River Amazon, 
appears to be an allied form. 
Of the foregoing species the following are most nearly 
related to Spongilla benguelensis, sp. n.:—S. bombayensis, 
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