142 Crozu.—Dimorphococcus Fritschii , a Nezv Colonial 
ponds that were examined, and thus appears to be chiefly a member of the 
limnoplankton ; in this respect contrasting with D. lunatus and D. cordatus> 
which are members of the helioplankton. These two latter species have 
not yet been recorded from Ceylon. 
The colonies of the new species, which may appropriately be named 
Dimorphococcus Fritschii , n. sp., were comparatively large, compact, com¬ 
pound groups. These were ellipsoidal in form, 85-100 fj. in length, 70-90 \x 
in width. Each group was composed of partial colonies of four cells each, 
embedded in definite colonial mucilage (see A in figure). . The cells of each 
partial colony were clearly dimorphous, the members of one pair being 
heart-shaped, the members of the alternating pair cylindric and slightly ‘ 
A. Portion of total colony. B. Portion of skeletal systems of colony dissected out. c. and D. 
Side and front view of cylindric cell. e. and F. Side and front view of cordate cell. (Specimen 
from Tank Borlasgama, near Colombo.) 
bent inwards. The cells were 12-20 y in height, the width of the cylindric 
ones being 5-6 fi. Each cell was borne on a short mucilage stalk and had a 
small lappet at its point of attachment (see C-F in figure). 
All the colonies observed were of regular ellipsoidal form ; the dimen¬ 
sions of the colony giyen above are for well-grown specimens of sixty-four to 
128 cells. From actual countings it would appear that the numbers men¬ 
tioned often actually occur, i. e. the cells of a colony all belong to the same 
generation. This results from the fact that the cell-divisions are approxi¬ 
mately simultaneous in all the cells of the colony, and here D. Fritschii may 
be contrasted with D. lunatus , A. Br. The regular form of the colonies in 
D. Fritschii is correlated with this fact. 
There was a definite enveloping mucilage as in Dictyosphacrium. This 
can be seen well in glycerine jelly preparations. The presence of enveloping 
