3io 
THE TANGANYIKA PROBLEM. 
than the Spongillidae are usually supposed to have. As a 
matter of fact, it is difficult to make out what structural 
reasons there are for retaining the family Spongillidse. It is 
not at all improbable that, when they are more carefully 
studied, they will be distributed among the several genera 
of the Homorrhaphidse. But as our knowledge has not yet 
attained a stage which will enable us to do this, it is deemed 
advisable for the present to place this new species among 
the Spongillidse, and to retain that assemblage of sponges 
as a family, however artificial it may be. 
Spongilla moorei appears to be more closely related to 
Spongilla aspinosa (Potts) than to any other species of the 
Spongillinse. Both species agree in possessing spicules 
which are smooth, straight or curved, and for the most part 
rather abruptly pointed. Malformed spicules, as they are 
described by Potts, are found in both, but they appear to be 
more numerous and more complicated in Spongilla moorei 
than in Spongilla aspinosa. Further, both species produce 
gemmules which are small in size, spherical in shape, and 
supplied with a thin crust which is not protected by spicules 
characteristic of the gemmule, but by the ordinary skeleton 
spicules. Though the gemmules are few in Spongilla 
aspinosa , they are more numerous than in Spongilla moorei , 
a feature which may be explained either by the lesser 
importance and consequent scarcity of the gemmule in the 
latter species, or simply by the season at which the material 
was collected. 
Spongilla aspinosa differs from Spongilla moorei in that it 
possesses small flesh spicules, which lie on the dermal mem- 
brane and among the smooth, slender skeleton spicules. 
These small spicules are not found in Spongilla moorei , unless 
they are represented by those which are drawn in Fig. 2 — b., 
which is probably the case. However, it must be admitted, 
