255 
HERPETOMONADS FROM THE ALIMENTARY 
TRACT OF CERTAIN DUNG-FLIES. 
By DORIS L. MACKINNON, B.Sc. 
(.Assistant in the Zoology Department, University College, Dundee.) 
(With Plate XIX and 4 Text-figures.) 
Introduction. 
In 1903 Leger pointed out that a flagellate apparently identical 
with Herpetomonas muscae-domesticcie, Burnett, may occur in other 
species of flies frequenting the neighbourhood of houses. The species 
found to be infected were Homalomyia scalaris, F., Pollenia rudis, F. 
and Theicomyza fusca, Macq. Beyond certain slight variations of form, 
the parasites from the different hosts showed no noteworthy morpho¬ 
logical deviation from the type species. 
Roubaud (1908) has also recorded H. muscae-domesticcie as occurring 
along with Herpetomonas ( Leptomonas) mesnili from species of Lucilia, 
and with Herpetomonas ( Leptomonas ) mirabilis from Pycnosoma 
putorium. 
The list of herpetomonads from insects steadily increases, and there 
is at present too great a tendency to regard each new herpetomonas 
“find” as a separate species peculiar to the host. Where the generic 
name of the host is used in forming the specific name of the parasite 
this custom is convenient enough, affording as it does a ready index of 
distribution: where the specific name is more fanciful, there is less to 
be said for it. In either case, until more of the known forms have had 
their life-cycles worked out, it must be admitted that the arrangement 
is artificial and should be looked on as tentative. 
I have recently found flagellates resembling Herpetomonas muscae- 
domesticcie in three dung-flies— Scatophciga lutaria, F., Neuroctena anilis, 
