THE TANGANYIKA PROBLEM. 
3 2 3 
POTAMOLEPIS WELTNERI, MOORE. 
With respect to this chrious form nothing more can at present be said than that 
it is a sponge growing in the deep water of lake Tanganyika ; that in the single 
specimen obtained it appears as a thin brown encrustation on a Paramelania shell ; 
that it has thick, slightly curved spicules which, unlike those of Potamolepis leub- 
nitzice, are slightly swollen at the ends, and that in general the enlarged ends of 
these spicules are micropunctate. It should, however, be noted that the character- 
istic spicules of this new form are closely similar to those of the old fossil genus 
Renieria. 
PROTOZOA. 
With respect to the unicellular organisms which are found 
in Lake Tanganyika, I have encountered only two forms 
which seem to call for any special mention. It may be 
remembered that, in Livingstone’s diary of his last journey, 
the explorer noticed that at times the surface of Tanyganyika 
was at times covered with what he called a “yellow scum,” 
and which, he says, he thought to be of “vegetable origin.” 
