3t) Gerald F. HiU: 



1 and 2, when compared with tliose of uii(h)u])ted H. niuscae in tlie- 

 same stage of development (Table No. 1), agree closely with that 

 species, to which they undoubtedly belon«^. 



On the other hand, the measurements of Specimens 8-6 (Table- 

 No. 5) do not agree with those of Specimens 1 and 2 of the same- 

 table, but they agree fairly closely with undoubted specimens of H.. 

 microstoma in a similar stage of development (see Table 2), and 

 there is no doubt in the writer's mind that they are referable to- 

 the last-named species and to the stage of that species preceding the- 

 appearance of spines under the cuticle at the tip of the tail. 



It was not noted wliether both species of Habronema occurred in- 

 any individual fly. In lable No. 6 measurements and details are 

 given of eleven larval Habronema from Stomoxys calcitrans flies- 

 bred from the same culture (February 11th). A comparison of these- 

 measurements with those of undoubted H. microstoma (Table No. 

 2), and H. muscae (Table 1) leaves little doubt but that they are- 

 I'eferable to the former species only. 



Experiment No. 16. 



Embryos from gravid H. muscae and H. microstoma were- 

 liberated in sterilized faeces on January 11 and 14th respectively, 

 and incubated until January 16th. On January 14th and subse- 

 quent days larval Musca domestica and Stomoxys calcitrans, which 

 hatched on January 7th, were fed upon the infected matter and 

 of the resulting flies one M. domestica and twenty S. calcitrans 

 were examined and found to be infected on January 29th and 30th. 



The measurements of four Ha])ronema larvae from the Musca 

 domestica fly are given in Table No. 7, the measurements of the- 

 remaining three being omitted on account of their agreement with 

 Specimen No. 2 in the above table. It will be seen by comparing 

 these measurements with those shown in Tables Nos. 1 and 2, that 

 the larvae found in this fly were almost certainly H. muscae. If a 

 further comparison is made between lable 8, w^hich gives the 

 "measurements of 6 Habronema larvae from Stomoxys flies (30th 

 January), and Tables Nos. 1, 2 and 7, it will be found that the 

 evidence is strongly in favour of these larvae (Table 8) being 

 referable to H. microstoma. 



These expei-inients confirm the fact that the final larval 

 stage of H. microstoma in the fly may be attained in the body of 

 Musca domestica as well as in Stomoxys calcitrans, while previous 

 experiments (7, 8, and 14) seemed to show that such was not the case.. 



