Zygnema] x. zygnemace^ (West). 339 



3. Zygnematis sp. W. et G. S. West, I.e. 



PuNGO Andongo. — Cum Scytommate in Pedra Songue ; April 1857. 

 No. 153. 



5. SPIROGYRA Link (1820). 



1. Spirogyrae sp. W. et G. 8. West in Journ. Bot. 1897, p. 40. 

 HuiLLA. — Inter alias algas in uliginosia editioribus prope Humpata, 



Empalanca et Lopollo ; May 1860. No. 15. Not in sufficient quantity 

 for absolute specific determination. 



2. Spirogyrse sp. W. et G. S. West, I.e. 



PuNGO Andongo. — Inter Batrachospermum nigresceiis in flum. 

 Cuanza ; March 1857. No. 104. Ad rupes humidas juxta flum. 

 Cuanza ; March 1857. No. 156. 



GoLUNGO Alto. Freq. in semistagnantibus ad ripas Rivi Quiapoze, 

 Caminho (road) para Mussengue ; Sept. 1856. No. 207. 



3. Spirogyrae sp. W. et G. S. West, I.e. 



PuNGO Andongo. — Ad ramulos Podostemacearum (Tristioha) in 

 rivulis PrsBsidii ; March 1857. No. 109. Nothing can be made out of 

 the specimens with any precision. 



4. S, negleeta KUtz. Species Algar. 441 (1849) ; Rabenh. Fl. 

 Europ. Algar. iii. 248 ; Petit, Spirog. de Paris, 26, t. ix. f. 1-5. 



Zygnema neglecta Hass. Brit. Freshw. Alg. 142, t. 23, f. 1-2 

 (1845). 



Var. ternata W. et G. S. West in Journ. Bot. 1897, p. 41. 



5. ternata Eipart in Bull. Soc. Bot. Fr. xxiii. 162 (1876) ; Petit, 

 I.e., 26, t. viii. f. 4-7. 



HuiLLA. — Frequentissima post pluv. autumnal, ad margines rivu- 

 lorum prope Lopollo ; April 1860. No. 185. 



5. Spirogyrse sp. W. et G. S. West, I.e. 



Ptingo Andongo. — Inter Batrachospermum nigrescens in riv. Cuanza ; 

 March 1857. No. 104. 



6. S. angolensis Welw. ex W. et G. S. West in Journ. Bot. 

 1897, p. 41. 



LoANDA. — Cum Microspora fontinali in aquis stagnorum puris 

 (Cazimba) urbis Loanda ; June 1858. No. 124. In stagnis artifici- 

 alibus (Represa de Manuel Pereira van Hunen) circa Loandam ; 

 July 1854. No. 193. Etiam No. 103. 



The very dark-coloured conjugating filaments and the form of 

 the zygospores characterise this species. S. arcta (Ag.) Kiitz , to 

 which No. 193 was relet red by Welwitsch, is a much smaller plant 

 with but one chromatophore, and the conjugating filaments are not 

 dark-coloured. 



7. S. Welwitschii W. et G. S. West in Journ. Bot. 1897, p. 41. 

 LoANDA. — Sp. denso agmine crescena, nubecularum amoeniss. virid. 



ad instar aquis innatans ; in stagnis artificialibus circa Loandam 

 (Represa de M. Pereira van Hufien) c. S. angolensi Welw. ; July 1854. 

 No. 103. 



This species approaches S. decimina (Miill.) Kiitz. (to which 

 Welwitsch had referred it) and S. neglecta (Hasa.) Kiitz. ; it differs 

 from the former in its much greater thickness, shorter cells, and 



