28 



(2) Placed obliquely at one end of the corpuscle, 8 to 10 /x 



long, coarse masses of melanin. 



(3) Elongated oval, 12 x 5*2 /x, placed alongside the host- 



nucleus, scattered fine grains of pigment. 



(4) Oval, tending to curl round the ends of the host- 



nucleus, 13'8 /x long. 

 These parasites are much larger than the Plasmodium 

 we have found in sparrows in Sydney. They are also 

 larger than the Jlalteridm we have met with. Gil- 

 ruth, Sweet, and Dodd (Proc. Roy. Soc, Vic, xxiii., 

 n.s. p. 231) have recorded P. hiziurae from the 

 musk-duck, Biziura lohata. This latter species is 8'5 to 

 10 X 4*8 to 9*7 /x, displaces the host-nucleus, and causes 

 slight enlargement of the infected cells from 13 "5 to 14*2 x 

 7*8 to 8*5 /x, to 15*6 x 9*7 to 10*6 /x. As the musk-duck 

 inhabits the same localities as the black swan, ib seems possible, 

 in spite of slight differences in size and shape, that our parasite 

 (if a true Plasmodium, and not a Halteridium) is also P. 

 ■hiziurae, under which designation it is provisionally placed. 



(2) Plasmodium passeris, from Passer domesficus (House 

 Sparrow). — In the Proceedings of the Linnean Society of New 

 South Wales, in 1909, vol. xxxiv., p. 505, Dr. Johnston and 

 myself have recorded the presence of a malarial parasite in 

 sparrows in Sydney. Another instance of infection has been 

 met with, a few red cells in one of two sparrows obtained in 

 October, 1914, showing spherical forms of about 4*8 /x diameter 

 at one end of the host-cell, displacing its nucleus. There were 

 a few fine scattered grains of pigment. It is of interest to 

 note that so far no indigenous species of birds in the neighbour- 

 hood of Sydney has- shown an infestation by a Plasmodium, 

 whilst this parasite, presumably imported into Australia with 

 its present host, must have existed in Sydney for at least 

 half a century, and probably for longer (no sparrows have 

 been introduced into Australia of recent years). Notwith- 

 standing apparently ample opportunities for transmission to 

 other birds, this seems not to have been achieved, either because 

 the parasite is specific to its passerine host, or because the 

 invertebrate host has opportunities of biting sparrows much 

 more frequently than other birds. An intermediate host like 

 the mosquito, Culer fati(/ans, would fulfil this latter role, since 

 it confines its activities to the immediate neighbourhood ci 

 houses to which few native birds resort. 



II. — Halteridium. 



There are several additional infected species to be recorded, 

 as well as further records of species already shown to be 

 infected : — 



