309 



CHAPTER XV. 



THE SPONGES OF LAKE TANGANYIKA. 



The sponges which were obtained during the Tanganyika 

 expeditions from that lake itself appear to consist of three 

 distinct forms. Two of these new species were examined 

 and described by Mr. Richard Evans under the names of 

 Spongilla moorei and Spongilla tanganyikce ; but besides 

 these among the material obtained during the first expedi- 

 tion there were encountered the spicules of a third form 

 embedded in the mud of the lake. The character of these 

 spicules, it seems, might, with equal propriety, suggest that 

 the sponge to which they belong is allied either to the New 

 World genus, Uruguay a or to the Congo genus Potamolepis. 

 As, however, nothing but the spicules had been obtained, 

 Mr. Evans left the form unnamed. During the second 

 Tanganyika expedition a small specimen of this third 

 species was dredged alive from great depths adhering to a 

 Paramelania shell, and this material was sent eventually to 

 Herr Weltner in Berlin, who replies that the sponge is 

 undoubtedly a new form, the framework being very similar 

 to Spongilla bohmii. The sponge, however, still remains 

 nameless, and as this is most inconvenient, I propose the 

 specific term weltneri, leaving the form for the present as a 

 member of the genus Potamolepis. 



