STUDIES ON PARASITIC PROTOZOA. 
297 
Studies on Parasitic Protozoa. 
I. The Flagellate Polymastix and its AflBlnities with the 
Trichonymphida. 
By 
Doris L. Mackiniioii, B.8c., 
Assistant in the Zoology Department, University College, Dundee. 
With Plate 18 and 1 Text-figure. 
Introduction. 
The Protozoa known as Trichonymphidae, parasites of the 
gut of certain orthopterous insects, have for long presented 
difficulties to the systematist. 
The early observers of the Trichonymphids, Leidy and 
Grassi, worked chiefly on the more highly specialised genera, 
such as Pyrsonympha and Dinennympha, and not un- 
naturally they placed these forms among the Ciliata, to which 
they bear a strong superficial resemblance. Other authors, 
dissenting from this view, preferred to regard the Gregari- 
nida as the nearest allies of this perplexing group. 
Biitschli^s observations on Lop h onion as (1878), from the 
cockroach, put a different aspect on the case. This form, in 
most respects simpler, and probably more primitive, than the 
trichonymphids from termites, had obvious affinities with 
the Flagellata. Kent (1880) formed for it a special family, 
the Lophomonadidae, which he placed in the neighbour- 
hood of such flagellates ‘as Trichomonas, Tetramitus, 
and Hexamitus. Grassi discovered Joenia annectens 
(1885) which is a link between Lophomonas and the more 
