396 



TR YPA NO SO MID m 



outlined by Noller, while Minchin, had he lived, would probably 

 have brought forward one. 



In the Trypanosominse the definitive, and hence primitive, host 

 . is the invertebrate, and we should expect to find some trypanosomes 

 which were solely denizens of these animals, and apparently this 

 is so. Unfortunately, their full life-history still requires much 

 ) elucidation, but such forms as Cystotrypanosoma intestinale 

 Roubaud, 1911, are worthy of more consideration; and it is 

 obvious that such forms deserve separate classifications, and 

 should form part of a tribe — Cystotrypanece, with Cystotrypanosoma 

 as type genus and C. intestinale as type species. 



As evolution proceeds so life-histories tend to become compli- 

 cated. In this case the complication is the introduction of a verte- 

 brate intermediary host, and with the change in environment one 

 meets with the large, relatively slow-moving, trypanosome of the 

 cold-blooded vertebrate and the smaller, quicker-moving, trypano- 

 some of the warm-blooded vertebrate . They appear to us to deserve 

 to be ranked into tribes and to merit more study. The type of 

 the first is obviously Gluge's parasite, and of the second the organism 

 found, by one of us, to be the cause of sleeping sickness. 



These various ideas may be crystallized as follows — 



A. Live only in a definitive invertebrate host 



Type genus: Cystotrypanosoma Roubaud, iQii' — Tribe i, 



Cystotrypanece Chalmers, 1918. 

 Type species: C. w^^s/wa/g Roubaud, 1911. 



B. Live in a definitive invertebrate host and in a cold-blooded 



intermediate vertebrate host :— 

 Type genus: — Trypanosoma Gruby, i843' — ^Tribe 2, Try- 



panosomecB Chalmers, 1918. 

 Type species: — T. rotatorium Gruby, 1843. 



C. Live in a definitive invertebrate host and in a warm-blooded 



intermediate vertebrate host :— 

 Type genus: Castellanella Chalmers, 1918— Tribe 3, Try- 



pocastellanellece Chalmers, 1918. 

 Co-type species: C. gambiensis (Button, 1902). 



C. castellanii (Kruse, 1903). 



In the present work we are chiefly concerned with the third tribe, 

 ' Trypocastellanellece.' 



SERIES A: TRYPANOSOMES INFECTING INVERTEBRATA. 



TRIBE 1: CYSTOTRYPANE^. 



This tribe has not yet been fully studied, but provisionally it 

 can be classified, as follows: — 



