W. S. Patton 
143 
The full grown form of the genus Herpetomonas is characterised by a 
blepharoplast placed almost at the very extreme anterior end and with 
no signs of an undulatory membrane. The largest forms are found in 
this genus, for instance, H. musccie-domesticate 1 0 to 120 pt, including the 
flagellum. This genus occurs in the non-biting flies and plant-frequenting 
bugs. In Crithidia the blepharoplast is located near and anterior to the 
nucleus; there is also present what may be called a rudimentary undu¬ 
latory membrane. The parasites of this genus are found in the gut of the 
biting flies, in predatory and plant-frequenting bugs, in mosquitoes and 
in ticks. In Trypanosoma we have the blepharoplast placed at the very 
extreme posterior end and an undulatory membrane very well developed. 
These forms are parasitic in the vertebrates.” Donovan agrees with us 
that the type species of the genus Herpetomonas “ is not biflagellate as 
Prowazek has attempted to make out and such individuals are by far 
the most common kind met with in the gut of some Musca domestica.” 
