652 J. S. DIINKERLY. 



(PI. 31, figs;. 11-14) in the house-fly, Homalomyia canicu- 

 laris, shows that Rosenbiisch's Crithidia imiscas domes- 

 ticaa, and therefore probably Trypanosoma drosophilas 

 of Chattel! and Alihiire, are merely forms assumed by a 

 Leptomonas. 



Should Leptomonas or Herpetomonas be the name given 

 to these parasites of the Insecta ? The Leptomonas of 

 Saville Kent was described as being- of a size comparable 

 with that of the small Leptomonas, of, e.g., Homalomyia, 

 whereas Hei-petomonas was evidently a huge form. Again, 

 Leptomonas was said to form rosetLes. A diagnosis based on 

 moi-phological grounds is of more value than one depending 

 upon habitat. At present, therefore, Leptomonas wouhl 

 appear to be a correct name for the uniflagellate parasites 

 found in the gut of non-sanguivorous insects, including house- 

 flies, Pycnogonum (22), Bombyx (11), and in some plants (7), 

 while Herpetomonas may be retained as a provisional name 

 for a large form with peculiar flagellar apparatus and a com- 

 plicated life-history, as described by Prowazek. Should the 

 latter prove to be but a stage in the Leptomonas' life-history, 

 tlien Herpetomonas should be merged in Leptomonas, since 

 the latter would then have been the first which was accui'ately 

 described. Crithidia cannot be applied as a generic name to 

 any form, as it has simply been the name given to two stiiges 

 in the life-history of Leptomonas, or in other cases to what 

 are probably stages of Trypanosoma. That Leptomonas had 

 priority over Crithidia was pointed out by Hartmann and 

 Jollos (5), but it was not clear then that " Crithidia " was a 

 form in the Leptomonas' life-histoiy. 



A paper by Flu on parasites of the house-fly, ^fusca 

 domestica, appeared (' Centralblatt f. Bakt., etc.,' Bd. Ivii, 

 1911, p. 522) after this paper had been sent to press, and is 

 in the main confirmatory of the chief points emphasised aliove. 



Protozoological Laboratory, 

 Lister Institute, 



LOKDON. 



