374 FAMILY: TRYPANOSOMIDyE 



G. fusca, and G. tachinoides, where it may give rise to confusion with de- 

 velopmental stages of T. gamhiense and other trypanosomes. It occurs in 

 the trypanosome form as well as others, and cysts are said to be produced in 

 the rectum. Kleine and Taute (1911), and Kleine (1919a), working with bred 

 flies which were fed on a known infected crocodile, have demonstrated that 

 H. grayi is in reality the developmental form of T. l-ochi, the crocodile 

 trypanosome; while Lloyd, Johnson, Young, and Morrison (1924) have 

 shown that laboratory bred G. tachinoides become infected with H. grayi, 

 or flagellates indistinguishable from it, after feeding on monitors {Varanus 

 exanthematicus) harbouring T. varani, or on toads {Bufo regularis) harbour- 

 ing a trypanosome resembling T. varani, as well as on crocodiles. It 

 appears, therefore, that H. grayi represents the invertebrate phase of a 

 trypanosome, so that the alleged presence of encysted forms in the rectum 

 of the flies requires an explanation, as these stages are not known to occur 

 in the case of any other trypanosome. Fraser and Duke (19126) failed to 

 cause laboratory bred flies to infect themselves from the faeces of infected 

 flies. As explained above (p. 342), it seems probable that the supposed 

 cysts of H. grayi are not actually of this nature. Minchin, Gray, and 

 Tulloch (1906), and Minchin (1908) suggested that H. grayi might be a bird 

 trypanosome. Of this there is at present no direct evidence. 



The genus Cystotrypanosoma, as defined by Roubaud, corresponds with 

 the genus Herpetomonas as it is interpreted in this work. As members of 

 Roubaud's genus Cercoplasma produce cysts, the distinction between it 

 and the genus Cystotrypa?iosoma is not very clear. 



Patton's Genus Rhynchoidomonas. 



Pattou (1910a) described a flagellate which he had found in the Mal- 

 pighian tubes of Lucilia serenissitna of Madras, and which appeared to difler 

 from the well-recognized types. He described it under the generic name 

 of Bhynchotnonas, but as this was pre-occupied, later in the same year he 

 substituted the name Rhynchoidomonas (Fig. 174). The flagellates were 

 only seen in a single fly. Flagellates of the same type were seen by the 

 writer (1911) in the gut and Malpighian tubes of house flies in Bagdad. 

 These flagellates were also seen by Alexeieff (1911) in species of CaUiphora 

 and Lucilia in Europe (Fig. 155), and by Patton (1921) in another fly in 

 Madras. 



In the writer's experience (1911a) they occurred in association with 

 H. muscarum, and it was concluded that they represented developmental 

 stages of this common house-fly flagellate. Later, in Aleppo, the question 

 was again studied by the writer, and the view was adopted that the try- 

 panosome forms actually belonged to the cycle of H. muscarum, as every 

 stage in the migration backwards of the nucleus could be traced. 



