GENERA: HELKESIMASTIX AND TRIMITUS 633 



end (Fig. 260, A). It differs, liowever, in that the anterior flagellum is 

 exceedingly short, while the posterior flagellum is about the length of 

 the body. The axonemes appear to arise from the nuclear membrane as 

 in Gercomonas. Spherical encysted forms occur, and syngamy was observed 

 to take place by the gradual union of two individuals. Two species are 

 described, the smaller of which, H.fcvcicola, had an ovoid body measuring 

 4 to 6 microns in length. 



B. Cercomonadidae with Two Anterior Flagella. 



Genus: Trimitus Alexeieft", 1910. 



This genus was founded by Alexeieff (1910) for a small flagellate which 

 had two anteriorly directed flagella and one posteriorly directed, the 

 axoneme of which passed over the surface of the body. There is one 

 species, Trimitus motellce, which occurs in the intestine of Motella tricirrata, 

 a marine fish. One of the anterior flagella is about as long as the body 

 and the other about half this (Eig. 260, B). The posterior flagellum is a 

 thick one, which is attached to the body as in Gercomonas, and has a length 

 four or five times that of the body itself. There is a nucleus near the 

 anterior end of the flagellate, and near it a granule in which the axonemes 

 of the flagella originate. A similar flagellate was discovered by Duboscq 

 and Grasse (1923, 1924:) in the termite, Calotermes flavicollis, of France. 

 It resembled T. motellce of Alexeieff, except in the possession of an axostyle 

 and a small rod-like parabasal which was attached to the blepharoplast 

 (Fig. 279). They believe it possible that Alexeieff had overlooked these 

 structures, and think that the flagellate sometimes has two and at other 

 times three anterior flagella. In a later paper (1924a) they point out 

 that the flagellate, in their opinion, is merely a young form of Trichomonas 

 dogieli (see p. 675). 



Chalmers and Pekkola (1919) described as Dicercomonas siidanensis a 

 flagellate which they found in human faeces. The name was subsequently 

 (1919a) changed by them to Diplocercomonas sudanensis, as the name 

 Dicercomonas had been previously used (Diesing, 1865; Grassi, 1879). 

 According to their description, the flagellate resembles Gercomonas with 

 the exception that there are two anterior flagella instead of one. The 

 writer has been able to examine the original films, and finds two flagellates 

 are actually present. One of these is Tricercotnonas intestinalis, described 

 below, and the other Embadomonas intestinalis, and it is evidently owing 

 to the fact that the double nature of the infection was overlooked that the 

 presence of a new flagellate having the structure described above was 

 accepted. There were no flagellates present which had the characters of 

 Diplocercomonas sudanensis, except some examples of Tricercotnonas, in 

 which only two anterior flagella were visible. 



