1906.] OF THE THIRD TANGANYIKA EXPEDITION. 223 



in al! of which there is a skeleton of sti'ongyles. In none of these, 

 however, ai-e there two kinds of strongyles. In S. loricata 

 Weltner, in addition to large strongyles (220-260^ x 20 yu) there 

 is a smaller kind of megascleres (124^ x 7/u) with finely gra- 

 nular surface and swollen ends ; here the very difierent sizes of 

 the two kinds of spicules will at once serve to distinguish the 

 res]3ective species. 



Locality. — From stones dredged in a few fathoms, Niamkolo 

 Harbour, Lake Tanganyika. 



Spongilla biseeiata "Weltner. 



1895. Spongilla &zsermto Weltner, Arch. ISTaturg. 1895, (1) p. 138. 



1897. Spongilla hiseriata Weltner, Deutsch-Ost-Afrika, Bd. iv. 

 Die Coelenteraten und Schwamme des siissen Wassers Ost- 

 Afrikas, p. 6. 



1898. Spongilla hiseriata Vt'eltner, Mittheil. naturhist. Mus. 

 Hamburg, xv. Beiheft, p. 1. 



Dr. Ounnington's collection contains an example of this species 

 from Lake ISTyasa. 



The specimen is in the form of an irregular clump about 4 cm. 

 in diameter, growing round the stem of a reed. The sponge, 

 which is in spirit, is dirty gi'ey in colour, and is full of pale yellow 

 gemmules. 



An interesting additional fact to record is Di-. Ounnington's 

 observation that the colour of this specimen was bright gi-een when 

 alive. The large dry type specimen from Cairo is described by 

 Dr. Weltner as dirty white. 



Localities. — From swamp, Karonga, Lake Nyasa, 2/7/04 

 {Cunnington). From a pool at Cairo {Lnez and Stuhlmann). 



Spongilla rousseletii, sp. n. (Plate XYII. figs. 1-5.) 



Sponge in form of a whitish incrustation. 



Skeleton a network with longitudinal main and tranverse and 

 oblique secondary fibres formed of bundles of oxeas with very 

 little spongin. 



Spicules curved oxeas, 214 x 18*5ju. 



Gemmules spherical, with one or several pore-tubes, with a 

 thick coat of spongin and with gemmule-spicules in form of spined 

 micro-strongyles arranged tangentially in one or two layers. 



Locality. — Above Victoria Falls, Zambesi. (Collected by 

 Mr. C. F. Rousselet, Sept. 13, 1905.) 



Descrijition. — The new species is represented only by some small 

 fragments of dirty-white colour. Mr. Ptousselet, who kindly 

 entrusted me with the material for description, informed me that 



that the general surface of the spicules is not smooth, but fine-spined or granular 

 all over, just as in S. bohmii. There are no amphidisk flesh-spicules in the tiny 

 scrap which represents, I believe, the tj'pe specimen of Moore's species. S. bohmii 

 and P. tveltneri both come from the same region, the former from the Ugalla River, 

 a tributary of Tanganyika, and the latter from the lake itself. It would be well, 

 however, to wait till more material is available for examination before deciding 

 whether Fotamolepis tveltneri is a good species or otherwise. 



