268 WELWITSCn's AFEICAN freshwater ALGiE. 



tenacibus, olivaceo-viridibus ; filis dense iutricatis et flexuosis, 

 vaginis non visis ; trieliomatibus angustissimis, pallide rerngi- 

 nosis, cellulis ellipticis vel doliformibus, diametro circiter 1^-plo 

 longioribus ; heterocystis globosis, circiter diametro tricbomatis 

 duplo latioribus ; sporis subglobosis, leviter augulosis, episporio 

 glabro et acbroo. Crass, trich. 2-5 /x; diam. lieterocyst. 4-5 /x ; 

 diam. spor. 7*5-9'5 //. 



Piingo Andongo. Freq. ad rupes editiores vulcan. prope Ca- 

 bondo tempore pluvio, intra dies duas tresve ingente copia obvia ; 

 Febr. 1857. No. 21. 



The nearest species to this is N. Immifimim Carm., from which 

 it is distinguished by its very large coriaceous non-tuberculate 

 thaUus, by its constantly elliptical or doliform cells, and by its 

 larger heterocysts and spores. 



2. N. paradoxum Welw. MS. Thallis vix 1| mm. latis, gre- 

 gariis vel solitariis, olivaceo-viridibus et nigrescentibus, pcridermide 

 tenue et hyaline ; filis densissime intricatis, flexuosis et abrupte 

 contortis ; trieliomatibus uniformibus, feriiginosis, cellulis cylindricis, 

 quadratis vel diametro 1^-1^-plo longioribus ; heterocystis solitariis 

 (raro binis), oblongo-ellipticis et submagnis. Crass, trich. 3-5- 

 3-8 /a; long, heterocyst. 8-5-9*5 /x, lat. G*5-7'5 /x. 



Pungo Andongo. Ad mucos dense csespitosos juxta rivulos prope 

 Pedra Songue ; April 1857. No. 20. 



This species belongs to that division of the section Iluiiii/usa 

 with cylindrical cells. 



3. N. MuscoRUM Ag. Dlsjios. Alqar. Suec. 44 (1812) ; Kiitz. Tab. 

 Phyc. ii. (1850-2), 2, t. 5, f. iv; Born. & Flah. I.e. vii. 200-1 (1888). 

 Crass, trich. 3-5-3-G /x; diam. heterocyst. G /x. 



Pungo Andongo. Ad rupes schist, pr. Candumba ; Jan. 1857. 

 No. 22. Cambondo ; Febr. 1857. No. 285. 



4. N. BHNUTUM Desmaz. Plantes Cnjptog. clu Nord de la France, 

 fasc. xi. no. 501 (1831) ; Born. & Flah. /. c. 209 (1888). This is 

 not identified with certainty, as it was seen in very small quantity; 

 spores elliptical, concatenate, long. 5-5-5 jj., lat. 3'5-4-5 /x; crass, 

 trich. 2'5 /x. 



Mossamedes. Inter CEdogoninm sp. in stagnis puris ad ripas 

 flum. Bero ; Aug. 1859. No. 190. 



2. ANABiENA Bory (1822). 



1. ANABiENA sp. 



Golungo Alto. Specimens very fragmentary, and spores not 

 attached to tho trichomes. Crass, trich. 3-3-5 /x ; diam. heterocyst. 

 5-5-6-5 /x; long. spor. 23 /x, lat. 9-5 /x. 



Freq. sed cito marcescens ad latera rivuli Coango ; Aug. 1857. 

 No. 163. 



XIX. CAMPTOTKICHEiE. 



Ordo novus Hormogonearum Homocysteai-um ; fila brevia, vagi- 

 nata, irrcgulariter flexuosa, extremitates versus attenuata, serie 

 irregular! singula cellularum intra vaginam unamquamque, cellulis 

 hand uniformibus, vaginis delicatis et achrois. 



