364 FAMILY: TRYPANOSOMID.E 



that of Leidy (1856), who said he had frequently found Bodo muscarum 

 in the intestine of the house fly in immense quantity. Later Stein (1878) 

 referred to it as Cereomonas muscce domesticce, and gives Bodo 7nuscce 

 domesticce (Burnett) as a synonym, though, as noted above, Burnett 

 referred to it only as Bodo. Finally, Kent (1880) referred it to his genus 

 Herpetomonas, and called it H. muscce domesticce (Burnett), though this 

 specific name was really Stein's. It would seem, therefore, as pointed 

 out by Hoare (1924), that the correct name should be H. muscarum 

 Leidy, 1856, as there is no doubt that Leidy and Burnett were both 

 observing this flagellate, in spite of the fact that Becker (1923c) considers 

 it a nomen nudum. Grassi (1879a) referred to the flagellate as 

 Schedoacercomonas muscce domesticce, and in 1882 as Monomita muscarum. 

 The majority of observers refer to the organism as Herpetomonas muscce 

 domesticce. 



The members of this genus, as defined in this work, have not only 

 leptomonas and crithidia forms in their cycle of development, but also 

 trypanosomes forms. They are, nevertheless, purely invertebrate para- 

 sites, which pass from host to host in the encysted stage. In the writer's 

 opinion, the bulk of evidence is in favour of the view that the flagellate 

 of the house fly has a trypanosome stage occasionally, though it is most 

 usually seen in the leptomonas form. If it should be demonstrated that 

 the trypanosome forms which occur in the house fly in reality belong to 

 a distinct species of flagellate, then the generic name Herpetomonas 

 cannot be employed for the genus as here defined, and it will become 

 a synonym of Leptomonas. In this case, probably Patton's name Rhyn- 

 choidomonas (p. 374) would have to be employed. Whether the name 

 stands or not, it is an undoubted fact that there are many insect flagellates 

 which conform to the definition of the genus Herpetomotias as given here, 

 and which was emended in this sense by the writer (1913). The recent 

 work of Drbohlav (1925), who has obtained cultures of the flagellate of 

 Lucilia ccesar, aiiords a direct confirmation of the conclusions reached 

 here. He informs the writer that cultures commenced with a single 

 organism showed not only leptomonas, but also trypanosome forms. With 

 these cultures specially bred Musca domestica, as well as Fannia regina 

 and L. sericata, were infected. It may be concluded, therefore, that the 

 flagellate of the house fly is identical with that of L. ccesar, and has both 

 leptomonas and trypanosome stages in its life-history. 



Herpetomonas muscarum (Leidy, 1856). — This flagellate is very com- 

 mon in the intestine of the house fly, Musca domestica, in all parts of the 

 world (Figs. 159 and 169). In some localities, especially in the tropics, 

 practically every fly examined is found to be infected. It has been 

 described from a variety of hosts other than Musca domestica, but from 



