J3Y T. HARVEY JOHNSTON AND J. BURTON CLELAND. 507 



We are, therefore, unable to place our parasite under any of the 

 known forms, which seems to us remarkable in that the common 

 sparrow is not a native of Australia, and we should expect that 

 all its hsematozoa were known. It may be, of course, that this 

 parasite is not one imported with the sparrow, but acquired from 

 some other source, such as some Australian bird, in which it has 

 not yet been detected. On the other hand, since the sparrow was 

 introduced into Australia many years ago, the descendants of the 

 original pairs must now have reached the 60th or 70th o-enera- 

 tion; and the descendants of the parasites, if these were imported 

 with the originals, an enormously greater number of generations. 

 It is, therefore, possible, though perhaps improbable, that our 

 parasite represents a variety of P. prcecox, which has evolved 

 •during this period. 



Though, as we have elsewhere stated, we are adverse to species- 

 mongering, we think advantage follows the labelling, by specific 

 names, of parasites differing in detail from the description of the 

 type-species : by doing so, attention is called to them, and, when 

 monographing the groups takes place, they can, as future work 

 -decides, maintain their rank as true species, or sink their identity 

 under a synonym. We, therefore, propose, tentatively, the name 

 Plasmodium passeris for this species. 



We have examined a dozen sparrows, tinding the hfematozoon 

 in two. The intestine of one of the birds was infested with a 

 tapeworm, Monoj)ylidium passerinnm, not previouslv known from 

 Australia. 



The t3''pe-slide has ])een presented to the Australian Museum 

 and cotypes are being retained by the Bureau. 



S p i r o c h a e t e s in the c £e c a of M its decu ma nus 

 and M. rati n s. 



In the rats, JIus decumanus Pall., and Mus rattus Linn., 

 ■captured in Sydney, films made from the ca^cal contents and 

 stained by Giemsa's method, frequently show numerous verv 

 small spirochaetes, uniformly dispersed through the smear or 

 ■collected more or less in groups. These are necessarily often 



