THE JOURNAL OF BOTANY 
108 
Zygnema. 
Represented in four localities. Only in one case were fertile 
specimens observed, viz.:— 
Z. stellinum (Ag.) Kirchn. forma subtile Reinscli. Vegetative 
cells 15-16 /a in width, about 50 p, in length. The species showed 
scalariform conjugation and the typical zygospores. Tycholimnetic. 
Log. 56. Distr. Temperate. 
DesmidiaceaB. 
The majority are tycholimnetic and have been recorded by W. & 
G. S. West for the paddy-fields and other habitats, from which they 
doubtless may occasionally be distributed into the “tanks.” These 
usually afford scanty material, and probably many have been over¬ 
looked. There are also a few typical plankton species. A small 
number were not identified, owing to the difficulty 7 in obtaining relevant 
literature. Our lists show that many of the common Desmids of 
Ceylon are also widespread. They do not preclude endemism, although 
if endemics occur they play a very small part in the limnoplankton. 
Goxatozygon De Bary. 
%J 
G. Brebtssoni De Bary. The material when examined onlv 
showed isolated cells. Length 162 p, max. width 6 /x. Our specimens 
belong to the type-form although somewhat small. W. & Gf. S. 
West give length 162-288 p, breadth 6*8-10*8 p. The var. minuttim 
W. & G. 8. West is, however, given as 47*5-67*5 p in length, 4*2-7 /x 
in breadth. Log. 16 (rare). Distr. Bur., Greenland, India, Afr., 
N. Amer. 
G. pilostjm Wolle. Narrowest cells scarcely exceeding 6ju; 
West gives 10*5-15 p. Loc. 11, 24. Distr. Eur., N. & S. Amer., 
Java, India (incl. Ceylon). 
G. monot.enium De Bary. Loc. 8. Distr. Widespread in 
tropics. N. hemisphere to Greenland. 
Closterium Nitzsch. 
C. Kuetzingii Breb. Loc. 3, 11, 24. Distr. General (incl. 
Ceylon). 
C. Leibletnii Kuetz. Probably several forms ought to be dis¬ 
tinguished. Our specimens came within the range of variation 
described bv West. Loc. 9. Distr. General. 
t j 
C. libellula Focke. Loc. 44, 61. Distr. General (incl. 
Ceylon). 
C. Cynthia De Not. Loc. 6, 9, 61. Distr. General (incl. 
Ceylon). 
C. Ehrenbergti Menegh. Loc. 44, 59. Distr. General. 
Ck Jenneri lialfs. Loc. 44. Distr. General, especially Tropics. 
Triploceras Bail. 
T. gracile Bail. Loc. 56. Distr. Victoria, Ceylon, Hong-Kong. 
Micrasterias Ag. 
M. mahabtjleshawarensis Hobson. Loc. 27. Distr. Chiefly 
tropical. 
