TWO NEW SPONGILL^ FROM LAKE TANGANYIKA. 481 



IV. Description of Spongilla Tanganyika. 



Owing to the fact that there was but a small piece of this 

 sponge among the material presented to me for investigation, 



is impossible to make any statement with regard to its 

 external form and habits of growth. However, it may be 

 conjectured that in both respects it must have resembled 

 Spongilla moorei, since Mr. Moore failed to detect it as 

 a distinct form. Though the two species are probably similar 

 to one another in their habits of growth and external characters, 

 they are strikingly dissimilar in the characters of their indivi- 

 dual spicules, though the general arrangement of the spicules 

 in the fibres and of the fibres at large is strikingly alike. 



The description of this species must, of necessity, be brief. 

 The same plan will be followed as far as possible as in the case 

 of the description given of Spon gilla moorei. 



(1) The skeleton will be described under the following 

 heading : 



(a) Spicules. 



(b) Arrangement of spicules, &c. 



(c) Spongin. 



(a) Spicules. — It may be safely stated that there are 

 megascleres and microscleres in this sponge. The megascleres 

 consist of amphistrongyla and amphitornota, which are for 

 the most part thickly covered with small spines. In addition 

 to these there are a few smooth or sparsely spined amphioxea 

 (PI. 38, fig. 10, a, /, g, h — I, and o — q). A few irregularly 

 shaped spicules, which appear to be the result of fusion, 

 are present (PI. 38, fig. 10, m). The microscleres are much 

 slenderer than the megascleres, though they almost equal 

 them in length. They are always smooth and slightly curved 

 (PI. 38, fig. 10, n). 



(b) The General Arrangement. — The arrangement of the 

 spicules does not differ materially from that already described 

 in Spongilla moorei. The spiny amphistrongyla and 

 amphitornota, together with a few smooth or sparsely spined 

 amphioxea, are arranged with their axes parallel to one another 



