BY T. HARVEY JOHNSTON AND M. J. BANCKOFT. 



1 



tsix in the thorax and three in the abdomen, nialdng a total 

 of 40, of which 42 were H. megastoma and H. muscce. 



Experiment IV. — During September, 1919, a few 

 larvae found in cow dung were collected and transferred 

 to horse dung as in the tAvo preceding experiments. Seven 

 flies were examined, all proving to be fairly heavily infected 

 with Habronema of both species. 



Experiment V. — Seventeen pupa? and one fly bred in 

 horse dvmg from various sources were examined, one fly 

 and one pupa were uninfected ; the remaining pu^DiV were 

 infected with from 20 to 60 Habronema. 



Thus out of 58 specimens of M. fergusoni, no less than 

 55 (95 per cent.) became infected when given the oppor- 

 tunity. 



II. — MuscA VETUSTissiMA Walker. 

 Captured flies (Eidsvold). 

 Specimens of this fl}' Avere captured in the same manner 

 as those of J/, fergusoni. The species, though common 

 in the Eidsvold district during the late spring, summer 

 and autumn, Avas A'ery scarce throughout the Avinter and 

 early spring. M. fergusoni, on the other hand, Avas plentiful 

 throughout the year Avith the exception of a feAv Aveeks 

 in the middle of Avinter (July-August, 1919). 



Of 280 specimens dissected, 14 Avere found to harbour 

 Habronema, i.e., 5 \)GV cent. In seA-en cases no record 

 of the particular species AAas kept ; in three cases the 

 worms Avere too small for identification ; of the remaining 

 four cases, H. muscce occiu'red alone tAvice, H. megastoma, 



