122 WELWITSCh's AFEICAN freshwater AI.G;E. 



Var. ELONGATUM Klebs, l. c. i. iii. f. 53. Long. 3J:-5-38 /x ; lat. 

 23-25 /i; lat. isthm. 11-5-12-5 /x; crass. 18-5 /x. 



Huilla. In uliginosis editioribus prope Humpata, Empalanca 

 et Lopollo ; May 1860. No. 15. 



45. C. coNCENTRicuM W. B. Tum. in A*. Sv. Vet.-Akad. Handl. 

 Bd. 25, no. 5, 62, t. ix. f. 11 (1893). 



Var. RADiATUM, var. n. (tab. 368, fig. 10). Var. miilte minor, 

 granulis minutis radiatim et concentrice ordinatis. Long. 13-5-15 /x ; 

 lat. ll-5-13"5 /x ; lat. isthm. 3-3-5 i/.; crass. 7-5 /x. 



Huilla. In uliginosis editioribus prope Humpata, Empalanca 

 et Lopollo ; May 1860. No. 15. 



46. C. Blyttii Wille in VUl.-Seisk. Forhandl. Christlania, no. 11, 

 25, t. i. f. 7 (1880). Long. 15 ^; lat. 12 ^; lat. isthm. 4 /^ ; 

 crass. 8 /x. 



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



47. C. suBcosTATUM Nordst. in Ofo. K. Vet.-Akad. Fork. no. 6, 

 37-8, t. xii. f. 13 (1876). 



Forma biinor West & G. S. West in Joiirn. Bot. xxxiv. 379, 

 t. 361, f. 15 (1896). Long. 19 /x; lat. 185 /x ; lat. isthm. 5-5 /x ; 

 crass. 10-5 /x. 



Mossamedes. Inter Charas in rivo Caroca pr. Cabo negro ; 

 Sept. 1859. No. 19. 



48. C. ALATUM Kirchn. in Cohn, Kryptoqamen-flora von Schlesien, 

 Zweit. Bd., 153 (1878). Long. 23-24 /x; lat. 19-21 /x; lat. isthm. 

 6-5 /*; crass. 10-5 /x. 



Loanda. In stagnis ; Febr. 1858. No. 136. 



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



Var. suBOBLONGUM var. n. Var. semicellulis angustioribus, 

 angulis basalibus rectangularibus, crenis basalibus tricrenulatis. 

 Long. 21 /x ; lat. 17 /x; lat. isthm. 5-5 /x; crass. 9*5 [a. 



Puugo Andongo. Ad ramulos Podostemacearum in rivulis ; 

 March 1857. No. 105. 



49. C. subtriordinatum, sp. n. (tab. 368, fig. 11). C. parvum, 

 tarn lougiuu quam latum, profuude constrictum, sinu lineari ex- 

 trorsum aperto ; semicellulfe transverse oblongo-ellipticje, lateribus 

 rotundatis cum granulis minimis 9, apicibus rectis glabrisque, intra 

 margiuem lateralem unumquemque granulis subordinatis instructae, 

 in centro seriebus tribus verrucarum quadratarum transverse ordi- 

 natis (3 in seriebus inferioribus, 2 in serie superiori); a vertice visas 

 ellipticae, ad medium utrobique verrucis tribus instructs, polis 

 minute granulatis ; a latere visfe depresso-globosfe, lateribus tri- 

 crenatis, apicibus glabris, intra margines granulis subordinatis 

 instructae. Long. 26 /x ; lat. 25*5 /x ; lat. isthm. 9-5 /x ; crass. 17 /x. 



Pungo Andongo. In stagnis prope Anbilla (Condo) ; March 

 1857. No. 177. 



The nearest species to this is C. triordinatum West and G. S. 

 West (in Tram. Linn. Soc. ser. 2, v. 66, t. vii. f. 27), from which 

 it differs in its less wide cells, its rounded and not acute granules, 

 its smooth apex, and in its quadrate (not rounded) and fewer central 

 warts. 



(To be continued.) 



