TWO NEW SPONGTLL^ FROM LAKE TANGANYIKA. 485 



Lubomirskinse. On the other hand, were gemmules to be 

 found in any species of the Lubomirskinse, it would have to be 

 removed from that sub-family as at present defined. Conse- 

 quently I venture to suggest that the sub-family Lubomirskinse 

 should be abolished, and the species contained in it placed under 

 the Spongillinse, which then could be rearranged into a number 

 of genera according to the characters of the megascleres. 



Appendix on some Sponge Spicules found in the 

 Mud of Lake Tanganyika. 



Along with the sponge material which Mr. Moore entrusted 

 to Mr. Minchin, there was a microscopical slide with some of 

 the mud of Lake Tanganyika mounted on it. There were on 

 the slide, among other things, some sponge spicules which in 

 shape resemble those of the genera Uruguaya (Carter [3]) and 

 Potamolepis (Marshall [7]). They vary from '14 to '31 mm. in 

 length, and from "013 to '05 in breadth. A great number of 

 intermediate stages between the two extremes are present. 

 Some of the spicules seem to be " micropunctate.^^ They are 

 nearly always curved, though the amount of curvature varies 

 considerably. The smallest spicules are of even thickness 

 throughout, being amphistrongylote. The spicules of inter- 

 mediate size in some cases present the same form as the small 

 ones, but differ in other cases in that they are slightly swollen 

 at the ends. The largest spicules are in all cases club-shaped. 

 In passing from the smallest spicules to the largest there seems 

 to be a gradual change from amphistrongyla to amphitylota 

 (PI. 38, fig. 11). 



It is difficult even to suggest what these spicules are. From 

 their characters they might well be the spicules of a species 

 belonging to the genus Uruguaya. But as the species of this 

 genus belong to the New World, and those of Potamolepis to 

 the Old, their locality seems to favour the view that they are 

 the spicules of some Potamolepid sponge. The variation in 

 size increases our difficulty, for it is impossible to decide 

 whether the smallest forms are young spicules, or a different 

 class of spicules, belonging either to the same or to an entirely 



