340 A Critical Review, etc. 
bring forward another on the polyphyletic origin of the Trypanoso- 
matidae. Is the evidence to hand sufficient to justify this hypothesis ?, 
we think not. Chatton and Alilaire have only observed one stage of 
T. drosophilae, and we are not even told whether this is the adidt 
flagellate stage, so that it is difficult to accept the authors’ contention 
that this parasite is a true trypanosome. 
In the present state of our knowledge it is imperative that we should 
obtain accurate and detailed descriptions of the life-cycles of these 
flagellates of arthropods and leeches. It is also essential to determine 
the manner in which infection occurs. We may then be in a position 
to theorise on the structure and origin of the Trypanosomatidae and other 
allied forms. 
In the meantime we propose placing the following species in the 
genus Crithidia :— 
1. Crithidia fasciculata Leger, type species parasitic in the 
alimentary tract of Anopheles maculipennis. Only a part of the life- 
cycle of this parasite is known. Mezincesco (1908) in a recent paper 
refers to this flagellate as Trypanosoma culicis Novy (1907); Crithidia 
fasciculata of Novy, MacNeal and Torrey is obviously Herpetomonas 
culicis. 
2. Crithidia campanulata Leger, parasitic in the alimentary tract 
of Chironomus plumosus, life-cycle not known. 
3. Crithidia minuta Leger, parasitic in the intestine of Tabanus 
tergestinus, life-cycle not known. 
4. Crithidia subulata Leger, parasitic in the alimentary tract of 
Tabanus glaucopus and Hematopota italica, life-cycle not known. 
5. Crithidia gerridis Patton, parasitic in the alimentary tract of 
Gerris fossarum, life-cycle recently described (Patton). 
6. Crithidia tabani n. sp. Patton, parasitic in the alimentary tract 
of Tabanus hilarius, life-cycle will shortly be described in Archiv fur 
Protistenkunde. 
7. Crithidia grayi Novy, parasitic in the alimentary tract of 
Glossina palpalis and possibly other Glossinae, life-cycle partly known 
(Minchin). 
8. Crithidia tullochi Minchin, parasitic in the alimentary tract of 
Glossina palpalis and possibly other Glossinae. 
9. Crithidia sp. ?, parasitic in the alimentary tracts of Glossina 
fusca and Glossina morsitans, part of the life-cycle described by Stuhl- 
mann and Koch. 
10. Crithidia melophagia Flu, parasitic in the alimentary tract of 
