WELWITSCH's AFRICAN FRESHWATER ALG.E. 181 



bus ad angulos tres efc apicem. Long. 133 /x ; lat. G5/x ; lat. isthm. 

 27 ji ; crass, membr. 3 //., 



Huilla. Inter Utriculariam, Morro de Lopollo ; April, IHGO. 

 No. 179. 



This is very distinct from .S'. cosinaiiindes Nordst. (iu Viilmsl,-. 

 Mcdd.f. d. natiuli. Foren. (1869), no. 14-15, 223, t. iv. f. 13 (1870) ), 

 and it is diffei-ent in the form of its front view and in its membrane 

 from any species of (Josniariam. Biirgesen, in Vidensk. Mcdd. f. <l. 

 natnrh. Foren., Kjohen. 1890, 50 (1891), figures (under a wrongly 

 stated magnification !) under the name of S. cosmariuides forms 

 wliich he suggests may be trigonal and tetragonal forms of several 

 species of Cosniarium. His fig. 2 somewhat approaches this species 

 in form, but it has different basal angles, and a very different sinus. 



15. S. scrobiculatum, sp.u. (tab. 3G8, fig. 18). S. minutum, 

 ptene l^-plo longius quam latins, modice coustrictum, sinu aperto 

 subrectangulo ; semicelluhe subelliptic;i3, margiuibus inferioribus 

 subrectis ; a vertice vis^B trigon^e, lateribus subrectis, angulis late 

 rotundatis ; membrana subsparsim scrobiculata. Long. 23 /x ; lat. 

 15-5-18 |U, ; lat. isthm. 10 /x. 



Huilla. In uliginosis editioribus prope Humpata, Empalanca 

 et Lopollo; May 1860. No. 15. 



16. S. PUNCTULATUM Breb. in Ralfs, Brit. Desiii. 133, t. xxii. 

 f. 1 (1848). 



Forma S-i/ona. Long. 26 /x ; lat. 23 /x ; lat. isthm. 8 /x. 

 Puugo Andongo. In rivulis (Casalale) ; March 1857. No. 105. 

 Forma 4-;/ona. Long. 34 /x ; lat. 31 /x ; lat. isthm. 14-5 ju. 

 Huilla. In uliginosis editioribus prope Humpata, Empalanca 

 et Lopollo ; May 1860. No. 15. 



17. S. DiLATATUM Ehrenb. fiifus. 143, t. x. f. 13 (1838) ; Ralfs, 

 llrit. Jh'sin. 133, t. xxi. f. 8 (18i8). Long. 21 /x ; lat. 25 /x; lat. 

 isthm. 7*5 /x. 



Pungo Andongo. In rivulis (Casalabi) ; March 1857. No. 105. 



Var. iNsiGNis Kacib. in Itosjirawij Ahutd. Vinicj. Krahaw, \Vi/(hi(il. 

 Ill it.przi/r. ser. 2, t. ii. (vol. xxii.) 388, t. vii. f. 13 (1892). Long. 

 20-25 /x ; lat. 17-22 /x ; lat. isthm. 8-5-9-5 /x, 



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



18. 8. HEXACERUM (Ehrcub. ) Wittr. in Bill. t. K. Ycl.-Akad. 

 Ilandl. Bd. 1, no. 1, 51 (1872). Dcsniidium. .^ hexaceros Ehrenb. 

 Abhandl. Akad. Wissenschaft., Berlin, 1833, 293 (1835); Infus. 141, 

 t. X. f. 10 (1838). Long.' 15 /x ; lat. 21 /x ; lat. isthm. 5-5 /x. 



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



19. S. MICRON West & G. S. West in Joiirn. U. M. S. 159, t. iv. 

 f. 50-51 (1896). 



Var. ANGOLENSE, var. n. (tab. 368, fig, 19). Var. semicellulis 

 subdepressis, lateribus subrectis, angulis minus productis, spiuis 

 distincte lougioribug. Long. 14 /x ; lat. 17 /'- ; lat. istlnn. 4 /x. 



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



20. S. GuRGELiENSE Schmidle in (Jester reich. Botan. Zeitschr. 64, 

 t. xvi. f. 23, 24 (1896). 



