FRESHWATER ALG.-E OF THE SOUTH ORKNEYS. 129 



B. CONJUGATE. 



MESOT^ENIA CE&. 



30. MESOT/ENIUM ENDLICHERIANUM, Naeg., Gatt. einzell. Alg., 1849, p. 109, tab. G, B ; 

 West and West, Brit. Desm., 1904, p. 56, pi. iv., figs. 20, 21. 



Sample 15, fairly common ; samples 1 and 3 (yellow snow !), isolated. 



There appeared to be more than two pyrenoids. Cells 24-26 M long ; 8-9 n broad. 



31. CYLINDROCYSTIS BREBISSONII, Menegh., Monograph. Nostocli., 1842, p. 89, tab. xii., 

 fig. 13; West and West, Brit. Desm., 1904, p. 58, pi. iv., figs. 23-32. 



Sample 8, fairly common ; previously recorded from South Georgia (Reinsch). 

 Two elongated pyreuoids mostly very obvious; length of cells = 50-54 M ; 

 breadth = 1 3 M. 



32. CYLINDROCYSTIS CRASSA, De Bary, Conj., 1858, pp. 37, 74, tab. vii., fig. c, 1-2 ; 

 West and West, Brit. Desm., 1904, p. 59, pi. iv., figs. 33-38. 



Samples 8 and 9, fairly common. 



Cells 32-35 ^ long; 14-1 5 M broad. Two rounded pyreuoids. Cells occasionally 

 very slightly curved, with broadly rounded ends. 



ZYGNEMAGEM. 



33. MOUGEOTIA, sp. 



Sample 8 ; only one filament of four cells seen. 

 Cells 3 1 /UL broad ; six times as long. 



34. ZYGNEMA, sp. 



Sample 4 (red snow !) ; one very much shrunken filament of about twenty cells. 

 Diam. cell. = 28 M; cells of the same length or one and a half times as long as broad. 



C. HETEROKONT^E. 

 CONFERVACEjE. 



35. CONFERVA BOMBYCINA, Ag., Syst., p. 83, n. 10; Rabenh., Fl. Europ. Alg., iii., 

 1868, p. 323. 



Forma minor, Wille, Algol. Mitteil., Pringsli. Jahrb., xviii., p. 467. 

 Samples 8, 9, 10, and 15, rather rare. 

 Diam. cell 6 M ; two to three times as long. 



D. CYANOPHYCEyE (Myxophycea). 

 CHROOOOCOAGE^:. 



36. SYNKCHOCOCCUS ^RUGINOSUS, Naeg., Gatt. einzell. Alg., 1849, p. 56, tab. 1, E., 

 fig. 1. 



Sample 10, rather rare. 



Cells isolated or in twos ; diam. cell = 3 M 



VOL. III. 17 



