16 Gerald F. Hill: 



this term being more correctly used to designate one of the five 

 stages of increasing complexity of development characteristic of 

 nem.atodes, each of these being separated from its predecessor by a 

 distinct moult. 



The same author (1912, p. 78) records the occurrence of both 

 Habronema muscae and Habronema microstoma in horses and mules 

 in Algiers.^ 



Work upon somewhat similar lines to my own is being carried 

 out by Mr. L. B. Bull, B.V.Sc, at the Government Pathological 

 Laboratory, in Adelaide. A preliminary manuscript account of 

 this Mr. Bull has very courteously allowed me to read while in the 

 press, and also he has discussed certain points with me. 



2.— The Adult. 



Until very recently the presence of Habronema muscae in the 

 stomaeh of horses in Victoria has not been recognised, although H. 

 megastoma and H. microstoma have been well known. There is 

 little doubt, however, that this has been due to a lack of distinction 

 between H. muscae and H. microstoma, for since this investigation 

 has been in progress, H. muscae has been found to be much more 

 common than H. microstoma, and some specimens hitherto re- 

 garded as H. niicrostoma have turned out to be H. muscae on 

 closer examination. 



In tlie adult stage the parasite (H. muscae) occurs very frequently 

 in the stomachs ot* horses in Victoria. A census of the parasites 

 found in 39 horses' stomachs which were examined during the 

 progress of this work shows that 33 of these harboured H. muscae. 

 Further reference will be made to this in the general discussion 

 later on. 



In view O'f the excellent full description given by Ransom of 

 the structure of this parasite, it is quite unnecessary here to- 

 attempt to add anything to it. 



So far as is known, this species acts similarly to H. microstoma 

 in its host. 



3.— Record of Experiments, and Special Observations. 



A. To determine the relationship of H. muscae to Musca domes- 

 tica as an intermediate host. 



Experiment No. 1. 

 Embryos from numerous H. muscae were liberated in sterile 

 faeces at noon on October 30th, and incubated at a temperature 



