129 Jn two Freshwater Sponges from Africa. 
Jntil now, the occurrence of a freshwater sponge from 
Africa had never been proved, while recently North and South 
America and Asia (Borneo, India, Lake Baikal, Japan) had 
furnished numerous species ; so that Dr. Bohm’s find appears 
zoogeographically not unimportant. (Zool. Mus. Protozoa 
810.) 
On looking more closely, however, my attention having 
been arrested by the appearance of a strange spicule in a 
prepared specimen, I found a new and hitherto quite un- 
known species of Spongilla on almost every individual of S. 
nitens. It coats the underside of the much more massive 
S. nitens as an inconspicuous erust of only 1 millim. thick- 
ness, consisting of a very fine-meshed delicate framework. 
The magnificent gemmule are grouped in a single layer of 
from 8 to 12 within the skeleton, but at the same time much 
projecting from it; in several examples they are entirely 
wanting ; and where they are present there are always very 
few of them. 
A delicate homogeneous lamella sharply divides the two 
species. 
The skeleton-spicules are of the same form as in S, nitens, 
but, instead of being smooth, are studded with roundish flat- 
tened tubercles which at the ends approach considerably closer 
together; they are scarcely half as long as in that species. 
They are often accompanied by a four-times smaller amphi- 
discoid form. The shaft of these siliceous bodies is gently 
curved, and bears at some distance from the centre a small 
spherical elevation ; from a similar one at each end of the 
shaft proceed five short, pointed, recurved prongs, exactly as 
ina whorl. These double whorls lie close to the large spicules, 
and form with them the network, the threads of which consist 
mostly of only one spicule in thickness. The width of the 
meshes may amount to 200 millimetres. 
The gemmule have not the layer of parenchyma; the spi- 
cules he tangentially and in only a single layer; but they 
are densely crowded and at the same time minute; so that 
their number is very considerable and far exceeds a thousand 
in one gemmula. ‘There is perhaps a larger portion of the 
surface covered by the spicules than left free from them, in 
which they moreover frequently cross one another. Hach 
spicule is moderately curved, cylindrical, with only the last 
eighth or tenth part tapering to a point; the surface bears a 
moderate number of short acute spines, of which from 8 to 10 
may occupy the length, and about 50 the entire spicule. 
