African Freshwater Sponges. 95 
form from streams and rivers, and 4, elliptica, var. tubifera, 
Sowerby, a spined form from standing water. The fine shell 
on which the two new species of sponges are growing is 
spined, and therefore belongs to the latter variety, so that we 
may conclude that the sponges lived in still water. ‘The 
locality of the shell is given merely as Benguela. 
Shells in the museum collection belonging to the genera 
Mulleria- and Bartlettia from South America, which with 
Aitheria comprise the family Adthertide, were examined 
also, but without any further sponges being fonnd, 
The following seven species of sponges have up to the 
present been described from specimens growing on Aiheria 
shells: —Spongilla sumatrana, Weber, vars. « and 8, Weltner ; 
S. etherie, Annandale; S. schubotz?, Weltner; Corvo- 
spongitia loricata (Weltner), C. mecramphidiscoides, Weltner ; 
C. scabrispiculis, Annandale; and Potamolepis  stendelli, 
Jaffé. A specimen of Spongilla carter’, Bowerbank (fide 
Kirkpatrick), has also been found on one of these shells, 
Weltner (11), in a paper published in the year 1913, gives 
a complete list of the freshwater sponges known in Africa up 
tothattime. Twenty-four species and varicties are mentioned, 
Since then Dr. Annandale (5) has described two species and 
Jaffé (7) one species; these, with the two species now 
described, bring the total number of Atrican freshwater 
sponges known at the present time to twenty-nine species 
and varieties. Thus Africa already compares favourably 
as regards number of species with other parts of the world 
known to be rich in freshwater sponges, 
Spongilla (Huspongilla) mcrospiculata, sp. n. 
The sponge spreads in a fairly thick encrustation over 
about a third of the surface of the upper valve of an Atheria 
shell, and coats some of the spines to their summits. 
It is of a greyish-white colour in the dried state and is 
extremely hard tothe touch. The surface is raised up into 
small ridges and rather prominent spines. 
The skeleton is made up of very thick fibres, which con- 
sist of multiserially arranged spicules bound together by 
a considerable quantity of spongin. The main fibres run 
vertically upwards through the sponge, dividing from time to 
time, and their extremities project above the general surface 
of the sponge and form the spines just referred to. They are 
united by rather thinner fibres at right angles to them, which 
run only from one main fibre to the next and do not them- 
selves form continuous fibres. ‘he whole constitutes a 
dense firm network. 
