33 



WELWITSCH'S AFRICAN FRESHWATER ALG^. 



By W. West, F.L.S., and G. S. West, A.R.C.S. 



(Plates 365-369.) 



(Continued from p. 7.) 



V. — Ulotrichace^. 

 1. HoRMisciA Fries (1835) ; em. Aresch. (1866). 



1. H. suBTiLis (Kiiiz.) De Toni, Syll. Ak/. 159, 160 (1889). 

 Ulnthrix subtilis Kiitz. Phi/c. German. 197 ; Rabeuli. Flor. Eump. 

 Alf/ar. iii. 365. Crass, fil. 5-5-6 fx. 



Huilla. Frequens in pascuis pluv. autumnalibus frequentius 

 iuundatis, demum exsiccautibus ad lacum magnum de Ivantala, 

 inter Pi)ri>hy)-osiphoneiii Xotarisii; March 1860. No. 18. 



Pungo Andongo. In pascuis spongiosis breve graminosis juxta 

 rupes gig., May 1857. No. 111. 



Var. VARIABILIS (Kiitz.) Kirclui. in Cohn, Krypto/j.- Flora van 

 Schles. 77 (1878). UlothrLv variabilis Kiitz. Species Alyar. 346; 

 Rabenh. I. c. Crass, fil. 6*5 //. 



Pungo Andongo. Freq. temp. pluv. in summis rupib. ; Febr. 

 1857. No. 6. 



2. Stigeoclonium Kiitz. (1843). 



1. Stigeoclonium ? sp. 



Huilla. Fragments amongst Gonatonema tropicus, &c., Morro de 

 Lopollo ; Febr. 1860. Nos. 172 and 186. 



3. Psephotaxus, gen. n. 



Tballus subfilamentosus, epiphyticus ; fila brevissima, serie 

 3-7 cellularum formata, solitaria, subirregularia et flexuosa, 

 simplices vel pseudoramosa, in muco firmo achroo nidulantes ; 

 celluljB formarum et mngnitudinum variorum, subglobosa), elliptical, 

 oblougae vel subpyriformes, sfepe curvatos ; membraua cellularum 

 crassissima et insigne lamellosa ; contentum cellularum granu- 

 losum. Incremc ntum plantarum bipartitione cellularum intercalari. 



1. P. lamellosus, sp. unica. Character idem ac generis. Diam. 

 cell. 15-29 jx; long. cell. 15-45 jjl ; crass, membr. cell. 3-4 fx. 



Pungo Andongo. Alga epipliytica in Dichotriche (/j/jisophila (inter 

 ScytiDU'nia iiiijoclinius var. c/thnttf/rajilticimi et (iLdoyoniiDn tapcino- 

 sporum var. ani/olcnse) ad latera boreal, et occid. de Pedra Songue ; 

 April, 1857. No. 12. 



Huilla. In Scliizotriche natante in graminosis paludosis juxta 

 rivulum de Lopollo ; April 1860. No. 180. 



This is a most remarkable confervaceous alga, more especially 

 on account of its short filaments of irregular cells with thick 

 lamellose walls ; the filaments are enclosed in an irregular mucus 

 which seems to be formed from the outer lanielht of the cells. 

 One method of propagation is by the breaking up of the filaments 

 into their component cells, each of which by division then forms a 

 short irregular filament. 



Journal of Botany. — Vol. 35. [Feb. 1897.] d 



