116 WELWITSCh's AFKICAN freshwater ALGiE. 



semieellulae pyramido-semicirculares, apicibus subtruncatis, angulis 

 basalibus rotimdatis ; a vertice visae anguste ellipticfe ; a latere 

 visae ellipticfe, membrana crassa et dense scrobiculata. Long. 86 /j.; 

 lat. 25-26 fx; lat. isthm. 11-5 jj.; crass. 14 /*. 



Huilla. In paludibus exsiccandis ; April 1860. No. 176. 

 Lopollo ; Febr. 1860. No. 192. 



This is somewhat like C. nitididum De Not. in form, but the 

 very thick and scrobiculate membrane easily distinguishes it. 



15. C. trifossum, sp.n. (tab. 367, fig. 19). C. parvum, 1^-plo 

 longius quam latius, profundissime coustrictum, siuu angusto- 

 lineari extreme ampliato ; semicellul^e semiellipticffi et levissime 

 depressae ad apices, excavatione minime profunda in medio apicis 

 et excavatioue simili infra et juxta apicem utrobique ; a vertice et 

 latere vis^ ellipticfe ; membrana dense et minute punctata. Long. 

 19-23 /x; lat. 13-5-15 /x ; lat. isthm. 2-8-3-5 /u ; crass. 8-5 /u 



Huilla. Inter Utricnhriani, Morro de Lopollo ; April 1860. 

 No. 179. In paludibus exsiccandis ; April 1860. No. 176. Etiam 

 in graminosis paludosis juxta rivulum de Lopollo; April 1860. 

 No. 180. 



The three shallow notches seen in the front view of each semi- 

 cell are due to the presence of three grooves running at right angles 

 to both the longitudinal and transverse axes. 



16. C. GALEEiTuii Nordst. in Vidensk. Medd. Naturh. Form. 

 Kjohen. 1869, No. 14-15, 209-210, t. iii. f. 26 (1870). A form with 

 more rounded sides; long. 62 jx; lat. 46 /x; lat. isthm. 16 /x; crass. 

 28 /x. 



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



17. C. NiTiDULUM Not. Desm. Iial. 42, t. iii. f. 28 (1867). 

 C. rectosporum W. B. Turn, iu K. Sv. Vet.-Akad. HinuU. Bd. 25, 

 no. 5, 69, t. X. f. 16 (1893). Var. minor, apicibus cellularum 

 latioribus et constrictione multe profundiori. Long. 15-23 /x; lat. 

 12-16 /x; lat. apic. 7"5-ll-5 /x; lat. isthm. 1-8-2-7 /^- ; crass. 

 6-5-8-5 /x. 



Huilla. In paludibus exsiccandis ; April 1860. No. 176. 



18. C. scENEDESMUs Delp. in Memor. Accad. ScL Torino, ser. 2, 

 XXX. 5-6, t. vii. f. 28-84 (1878). 



Var. DORSiTRUNCATUM Nordst. iu K. Sv. Vet.-Akad. Handl. 

 Bd. xxii. no. 8, 59, t. iii. f. 15 (1888). A small form with a per- 

 fectly smooth membrane. Long. 22-25 /x ; lat. 26-27 /x ; lat. 

 isthm. 6"5-7'5 /x ; crass. 11*5 /x. 



Huilla. In paludibus exsiccandis ; April 1860. No. 176. 



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



19. C. sethiopicum, sp.n. (tab. 367, fig. 20). C. subparvum, 

 circiter IJ-plo longius quam latius, sinu lineari extremo leviter 

 ampliato; semicellulfe hexagono-semicirculares, angulis inferioribus 

 rectangularibus, marginibus lateralibus parallelis, marginibus su- 

 perioribus rectis, apicibus late truncatis, serie plicationum lougi- 

 tudinalem circiter 10 juxta sed intra apicem et margines superiores ; 

 a vertice visfe ellipticcis, polls subattenuatis et subtruncatis, a latere 

 visc^ subglobosfe, elevatione lata levi infra apicem utrobique ; mem 



