34# 
F. E. Fritsch. 
species of the genus and not in another indicates that some special 
feature is probably concerned. I am, however, at present unable 
to offer any further data on the subject. 
The commonest species of Cryptomonas appears to be C. ovata 
Ehrenb. I have repeatedly observed isolated individuals of this 
species from many localities in the neighbourhood of London, whilst 
a very small form appeared in large numbers in one of my algal 
cultures (Pig. 2, F, G). This form is 18-24/x long and 12/x broad, 
the cilia being about two-thirds as long as the body of the individual. 
The gullet is rather narrow and penetrates very deeply in most cases 
so as nearly to reach to the back end of the individual; it runs parallel 
to the body for the greater part of the length of the cell, but curves 
anteriorly so as to meet the emarginate front end approximately at 
right angles (Fig. 2, F, G). A central pyrenoid is a very prominent 
feature, whilst abundant starch-grains occur scattered through the 
cell; the bright body at the posterior end, usually regarded as the 
nucleus, is also plainly visible in all cases. In some individuals a 
second bright body, whose nature is doubtful, was observable in the 
anterior dorsal corner (Fig. 2, F). 
The form just described differs mainly from the published figures 
of C. ovata Ehrenb. in the narrow gullet; a minor point of difference 
lies in the fact that the emargination of the front end is but little 
pronounced. It is possible that these may be characteristics of a 
distinct variety, but I prefer for the present to regard them as merely 
marking a form of the species. 
I am indebted to Miss F. Rich, M.A., for some interesting 
material of Cryptomonas from Cow Pond, near Houghton-on-the-Hill 
not far from Leicester. 1 have unfortunately only seen this material 
in the preserved condition, and Flagellates are certainly best studied 
primarily in the fresh state. At least two forms of Cryptomonas 
were present; one of them (Fig. 2, H) was very scantily represented, 
the other (Fig. 2, C-E) in great abundance. To take the former 
first: it possesses characteristics which certainly seem to stamp it 
as new. Combined with a very marked protrusion of the dorsal 
anterior end, making the front edge of the organism as pronouncedly 
oblique as in extreme specimens of C. nasuta Pascher, we have a gullet 
whose characteristics are quite distinct. Commencing at the oblique 
anterior end it extends as a perfectly straight sac to the middle of 
the dorsal face of the organism which it almost reaches (Cf. Fig. 2, H). 
The cilia, which are slightly shorter than the body of the cell, arise 
as usual from the ventral edge of the gullet. The central pyrenoid 
is somewhat angular in outline. 1 will provisionally describe this 
