W. B. Crow 
64 
development. The genus Aphanocapsa, however, consists of a very 
heterogeneous assortment of forms some of which will doubtless fall 
into other genera when their life-history becomes fully known. The 
genetic connection of some supposed species of Aphanocapsa with 
other Chroococcaceae ( e.g . Chroococcus, Glceocapsa) is already estab¬ 
lished in some cases ( 5 ). The presence of pseudovacuoles, the cell size 
and the resemblance to M. flos-aquce in certain phases all point 
towards the fact that this new species is a true member of the genus 
Microcystis. 
Loc. Tank Mineri, Oct. 12th (water-bloom); tank Andankulam, 
Oct. 18th (water-bloom); rock pool in wet season of the year cer¬ 
tainly connected with tank Punchi-kekirawa close by, Sept. 28 th; 
Perithpan-pokuna near Isurumunija-temple at Anuradhapoora, 
Oct. 3rd. 
MICROCYSTIS PSEUDOFILAMENTOSA n.sp. 
Figs, e and / 
Colonies very long and narrow, consisting of a series of partial 
colonies, i.e. constricted at intervals, sometimes considerably widened 
at places and broken through or reticulate. Margin of colonial 
mucilage indistinct.. Cells 3-7 p, diam., spherical, with pseudo vacuoles. 
Colonies varying greatly in size, sometimes twenty times as long as 
wide, frequently 200-300p, in length; 20-30/x in width, the partial 
colonies being about equal in length and width. 
The colonies of the above species resemble those of M. stagnalis 
Lemm. in their elongated form but not in their segmented character. 
M. pseudofilamentosa is also distinguished from M. stagnalis by the 
size of its cells, which are more than twice as large as in the latter 
species, and in the presence of pseudovacuoles which do not occur 
in M. stagnalis. From M. ceruginosa our species is distinguished by 
the form of its colonies and by the more indistinct margin of the 
colonial mucilage. M. pseudofilamentosa y apart from the latter feature, 
would resemble, in form, certain string-like bodies described by 
Wesenburg-Lund for M. ceruginosa ( 9 ). But the mode of origin appears 
to be different in our specimens. Instead of arising as lateral out¬ 
growths from the rounded colonies of the ordinary Clathrocystis as 
described by Wesenburg-Lund for the forms referred to, our colonies 
would appear to break up frequently into their partial colonies which 
divide again to give elongated compound colonies much in the same 
way as a cell may divide up to form a filament. This character 
suggested the specific name given. M. pseudofilamentosa , in virtue 
