1906.] OF THE THIRD TANGA.W'IKA EX^EDITIO^^ 221 



Moliro, 24/10/09 ; No. 161, from rocks, shallow water, Chamkaluki, 

 15/11/04 (oemmules plentiful); ISTo. 173, from shells, dredged in 

 10 fms., Pemhe, 23/11/04; No. 593, lOfms., Mtondwe Bay. 



Spongilla TANGANYIKA Evans. (Plate XY. fig. 10.) 



1899. iSponglUa tanganyihm Evans, Quart. Journ. Micr. Sci. 

 vol. xli. p. 481, pi. xxxviii. figs. 9, 10. 



There are several small specimens, whole and in fragments, 

 of this species in Dr. Cunnington's Collection. Two of the 

 specimens (Nos. 163 and 224) are associated with Polyzoa, and 

 althongh there are, in each case, only a few crumbling fragments, 

 they are interesting, because in some respects they show an inter- 

 mediate condition between S. moorei and the present species. 

 The megascleres are spined as in aS*. tanganyikce, but more nearly 

 resemble the form of those of *S'. moorei. Thei'e are no stron- 

 gyles, for instance, their place being taken by spined tornotes. 

 Plate XV. fig. 10 shows a tornote on the way to becoming a 

 strongyle ; the sharp point of the oxea still j)ersists, though it 

 has nearly disappeared ; its complete disappearance would result 

 in the strongylate form. On account of the spined condition of 

 the spicules I have classed the specimens undei' S. tanganyika\ 

 The remaining specimens are in the form of small incrustations 

 on broken fragments of the shells of the Gasteropod Neothawma 

 tang any icensis together with incrustations of S. moorei. 



Specimens of these two species so closely resemble each other 

 externally that it is only possible to separate them by an exami- 

 nation of the spicules. The surface is uniformly level and finely 

 granulated, the granular appearance being due here, as in 

 ;S'. moorei, to the minute pi-ojecting tufts of the main longitudinal 

 spicule-bundles. The tufts only project the length of a spicule, 

 and differ slightly from those of ^S*. moorei in being composed 

 of only 1-3 in place of 2-5 spicules, a.nd in the spicules being- 

 adherent to each other along their whole length. 



As in S. moorei there is a basal spongin-lamella, but it is very 

 thin, nor are the spongin-fibres arising from it developed to the 

 same extent as in the first species ; at the same time, thei-e are 

 here also distinct spongin-fibres enclosing a core of spicules. 



There are no gemmules in any of Dr. Cunnington's specimens. 

 Those described by Evans in the type had only a thin chitinous 

 capsule, and were apparently very like those of S. moorei. 



Localities. — Lake Tanganyika, No. 163, associated with a Polyzoan, 

 from rocks, shallow water, Chamkaluki, 16/11/04; No. 224, with 

 Polyzoan, on shells, 20 fms., Mshale, 6/2/05 ; No. 593, dredged 

 in 10 fms., Mtondwe Bay. 



Spongilla cunningtoni, sp. n. (Plate XYI. figs. 1-6.) 



Sponge in form of a thin spreading ciaist. Surface smooth and 

 devoid of projecting spicules. Skeleton a network with triangular 

 and polygonal meshes, without distinct ma in and secondary fibres ; 

 dermal skeleton composed of a definite layer of horizontally 



