Air'cfin Freshwalcr Sjtntit/^-i. !.•."> 



form from sfrtsuns sind rivcry, and yZ/'. ellifin'cdj vju\ lulnftriij 

 Sowcrliv, a .sjtiiicd form fiom standing' \v:ittr. 'Ilu; fine shell 

 «>n wliicli I lie two new spfcicH of n|ioiii;('s me j^r«i\viii<^ i.s 

 spilled, and tlierelore l)clonj;.s to tlie lattei- varitty, so that \vc 

 may coiuliido that the .sp»>ii^M'.s lived in still Water. The 

 l"Cjdity of the shell is ^Mveii nuMcly as Beii;;uela. 



Shells in the musenin collection heloni^iii*^ to the pfcnpra 

 Mullerin mid Utniletihi IVomi South Amerita, which with 

 j^therix comprise the famdy ylCtheriida}, were examined 

 also, hut wiihout ai.y furilnr .>-poii;;es bein;^ found. 



The foilowiii^' seven Sjnci«'S of 8pon;i;e.s have up to the 

 present been deticrdjrd fr(»m speciinen.s growinj; o\\ JlCiheria 

 shells: — Sfiongllln t^uni'itrau'ij Weber, vars. a and ^, Weltiier ; 

 S. lethericv, Annandido ; 6'. schnbutzi, Weltuer ; Curv '- 

 afioiiqlUa lti7-iciitu ( W eltnt r), ('. hdivainjihuiiscnide.i^ AVeltn<r ; 

 C. scu^risjiicnlis^ Annaiidalc; and l^otainolcpis stendiUi^ 

 .Jaffe. A spfciuii n of S/ionr/iUii cartfn\ Biweibank {Jide 

 Kiikpntiick), has also been found ou one of these slndli, 



Weltner (il), in a paper published in the year li^Lii, gives 

 a complete list of the Iroshwa'er spou^^es known in Africa up 

 to that time. Twenty-f ur species and vari. ties are mentioned. 

 .Since then Dr. Annan<iule (5) has desciii>cd two species and 

 Jat!e (7) one species ; these, wiih the two species now 

 destiribed, bring the total numl)er of A'lican freshwater 

 sponges known at the present time to twejity-nine species 

 and varieties. Tlius Afiica aln'ady com|)ares favourably 

 as regards number of specii-s with 01 her parts ^of the world 

 known to be rich in frcshwaier sptmgos. 



Spont/illa (Eu.tj)on'/id(t) in icrospiculala, sp. n. 



The sponj^e s])reads in a fairly thick encrustation over 

 about a third of the surface of the upper valve of an ^Etlterli 

 shell, and coats some of the s|jin(S to their summits. 



It is of a greyisii-wliite colour in the dried state and is 

 extremely hard to the touch. The surface is raised up into 

 f^mall ridges and rather [)rouiinent spines. 



The skeleton is made up of veiy thick fibres, which con- 

 sist of niultiserially arranged spicules bound together by 

 a considerai)le quantity ot spongin. The main fibres run 

 vertically Ujnvards through the sponge, dividing from time to 

 time, and their extremities [iroject above the general surface 

 of the sponge and form the spines just referred to. Thty are 

 united by rather thinner fibres at right angles to them, which 

 run only frou) one main HIjre to the next and do not them- 

 selves form continuous fibres. The whole constitutes a 

 dense firm netwurk. 



