BY T. HARVEY JOHNSTON AND J. BURTON CLELAND. 503 



The nucleus of the adult parasite was seen as a large con- 

 spicuous mass (Giemsa's stain), generally centrally situated, 

 though in a few instances it was placed very obliquely. The 

 capsule was usually quite distinct, there being in most specimens 

 a considerable space between it and the enclosed parasite. 



Commonly the organism occupied nearly all the extranuclear 

 part of the leucocyte. Its position in the host varied considerably, 

 though the most usual position was parallel to the inner side of 

 the somewhat bean-shaped host-nucleus (fig. 6). At other times 

 the parasite was obliquely, and in a few cases transversely, placed 

 (fig.2). The host-nucleus was occasionally indented, especially 

 by the transversely situated forms (fig. 4), and in a few cases was 

 actually divided (fig. 3). 



Schaudinn has stated that a leucocytozoon is a stage in the life 

 cycle of a spirochaete or a trypanosome. If this be correct, 

 which seems to us to be improbable, may L. muris and Trypano- 

 soma leivisi be different phases of one organism % 



In the films from one of the infected rats, both L. muris and 

 T. leivisi were present, whilst in the other there were no 

 trypanosomes. 



Halteridium nettionis, sp.nov. — A blood-parasite of Nettion 

 (Anas) castaneum Eyton. 



(Plate xlviii., figs. 15-17.) 



An examination of blood-films from an Australian teal, 

 Nettion castaneum Eyton, New South Wales, prepared by the 

 Director of the Bureau in 1907, and handed to us for examina- 

 tion, revealed the presence of Halteridia. These differ from the 

 other Halteridia (//. chrysops, H. meliornis, H. geocichlce, H. phile- 

 mollis), which we have described(4) from Australian birds, in the 

 large size of the parasite as regards the host-cell, and by the 

 number and large size of the melanin-granules. The parasites 

 were not numerous, but two types could be distinguished, 

 extremes of which almost certainly represent the sexes, the 

 intermediate types perhaps the schizonts. 



