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A NEW FLAGELLATE (MACROSTOMA M ESN I LI N. Sp.) 
FROM THE HUMAN INTESTINE WITH SOME REMARKS 
ON THE SUPPOSED CYSTS OF TRICHOMONAS. 
C. M. WENYON, M.B., B.S., B.Sc., 
Protozoologist to the London School of Tropical Medicine. 
(Plate XYI, and 2 Text Figures.) 
The flagellate to be described in this paper was found in the faeces 
of a native of the Bahamas who was admitted to the Seamen’s Hospital, 
Albert Dock, in October, 1909. In the course of the examination of the 
perfectly fresh material it was noticed that numerous flagellates were 
swimming about. They were taken to be Trichomonas but on closer ex¬ 
amination they were seen to differ markedly from these. In the character 
of their movements there was little to distinguish them from Trichomonas 
except that the undulating membrane so characteristic of this genus 
appeared to be absent. The body is pear shaped and there are three 
long flagella directed forwards from the blunt end of the body. By the 
lashing of these three flagella the animal is drawn along with the blunt 
end in advance and at the same time revolves upon its longitudinal axis. 
A very characteristic feature is the presence of a very large cytostome 
extending from the base of the three flagella towards the posterior end of 
the body for about one half to two thirds of its length. The movements 
of the animals were at first so violent that great difficulty was experienced 
in making out the details of the anatomy, but as the faeces cooled their 
activities began to abate. It was then seen that the flagella was as long 
or longer than the body and that the large cytostome was arranged in a 
slightly spiral manner: that is to say it did not run directly parallel 
to the longitudinal axis of the body. The edges of the cytostome were 
produced into two lips which were very well shown when the animal was 
