WELWITSCH's AFRICAN FBESHWATER ALG/E. 85 



Huilla. lu uliginosis editioribus prope Humpata, Empalanca 

 et Lopollo ; May 1860. No. 15. 



Forma. A form with the lateral lobes partly subdivided. Long. 

 26 IX ; lat. 17 /x; lat. apic. 14-5 /jl; lat. isthm. 5-5 /x ; crass. 9*5 /x. 

 (Cfr. W. & G. S. West in Trans. Linn. Soc. 2 8er. v. t. ix. f. 16.1 



Huilla. Inter Gonatonema tropicum, Morro de Lopollo ; Febr. 

 1860. No. 186. 



15. E. tetragonum, sp. n. (tab. 366, fig. 10). E. minutum, 

 circiter l^^-plo longius quam latius, profnnde constrictum, sinu 

 linear! ; semicellulffi subrectangulares, apicem versus latiores, angulis 

 basalibus leviter rotundatis, lateribus subretusis in medio, dente 

 minuto ad angulum superiorem unumquemque, apice leviter con- 

 vexo et retuso in medio, seriebus duabus granulorum parvorum 

 trans angulum superiorem unumquemque, granulis 4 intra angulum 

 basalem unumquemque, et papilla in centro; a vertice visa ellipticte, 

 polls acutis dente parvo instructis, seriebus duabus transversis 

 granulorum ad polum unumquemque, papilla mediana utrobique 

 instructiB. Long. 18-19 /x; lat. has. semicell. 13-13'5 /x; lat. apic. 

 14-15 /x ; lat. isthm. 3'8-4-8 /;- ; crass. 9-5 /x. 



Libongo. Ad margines flum. Lifune ; Sept. 1858. No. 204. 

 Compare with E. denticidatuvi v. rectangulare West & G. S. West 

 in Tracts. Linn. Soc. 2nd ser. v. 53, t. vi. f. 21. 



16. E. bimorsum, sp.n. (tab. 366, fig. 17). E. subparvum, 

 If-plo longius quam latius, profunde constrictum, sinu angusto 

 extremo ampliato ; semicellulfe pyramidato-trapeziformes, angulis 

 basalibus rotundatis, lateribus rectis, incisuris parvis duabus et 

 promontoriis ^qualibus denticulatis tribus ad laterem unumquem- 

 que, dente parvo ad angulum superiorem unumquemque, incisura 

 profunda lineari ad medium apicis recti undulato-denticulati, intra 

 promontoria denticulis paucis, lis intra promontorium basalem 

 insignibus, verruca magna in centro infra incisuram apicalem ; 

 a vertice visje elliptico-oblongas excavationibus latis duabus utro- 

 bique, projectione centrali truncato-emarginata, polls late rotundatis 

 et undulato-denticulatis ; a latere visfe pyramidato-oblongffi apice 

 truncato denticulatoque, angulis basalibus denticulatis, projectione 

 truncato-emarginata in medio lateris glabri uniuscuj usque ; mem- 

 brana minute punctata. Long. 38 /x; lat. 23 /x ; lat. apic. 18 /x ; 

 lat. isthm. 6 /x ; crass. 17 /x. 



Huilla. In uliginosis editioribus prope Humpata, Empalanca 

 et Lopollo, plagas spongiosas unacum Eriocauloneis, Xyridibus et 

 Utriculariis constitueus ; May 1860. No. 15. 



This is very similar in outline to E. Turnerii West (in Jou);n. 

 Linn. Soc. xxix. 141, t. xx. f. 18), but differs totally in both vertical 

 and lateral views. 



17. E. subdivaricatum, sp.n. (tab. 366, fig. 9). E. parvum, 

 circiter 1^-plo longius quam latius, profunde constrictum, sinu 

 lineari et extrorsum leviter aperto ; semicellulre pyramidato-trapezi- 

 formes, sinibus duobus utrobique (eo infra apicem insigui), pro- 

 jectione mediana emarginata, angulis inferioribus superioribusque 

 mucronatis, granulis parvis 4 in margine apicis subconvexi, de- 



