BY T. HARVEY JOHNSTON AND M. J. BANCROFT. 49 



number of worms ranged from 1 to 16, with an average of 8. 

 The abdomen alone was infected t\Wce ; the head, proboscis 

 and abdomen once : while in the fly containing 16 worms — 

 the heaviest infection met with in any fly — all regions of 

 the body were infected, three parasites being present in the 

 head, four in the proboscis, three in the thorax and six in 

 the abdomen. 



M. terrce-regince. A single infected specimen of this 

 species was met with on March, 1919, when a fh" containing 

 four worms in the proboscis Avas dissected. 



In every case of infection in the three species dealt with, 

 the parasitised subject was a female i\y. Many more 

 females were dissected than males, since among flies captured 

 on stock the former sex predominates. However, the number 

 of males dissected was quite large enough to \\airant the 

 expectation that an occasional infected specimen would be 

 met with, at any rate during the latter part of 1919, when 

 the percentage of infected M. fergusoni remained high. 

 This, however, was not borne out by experience, although 

 Habroneraic infection occurred quite frequently among 

 males. Two sets of figures giving record of the sex of flies 

 {M. fergusoni) will illustrate this point. Out of 102 (seven 

 males and 95 females) dissected during May and June, 

 1919, three males and one female were infected A^th 

 Habronema spp. and four females with Agamosp' rura 

 muscarum) . During the last thi'ee and a-half months of 

 1919 out of 238 flies (21 males and 217 females) 31 females 

 were infected with Agamosijirura muscarum, no other 

 nematodes being met with. 



Description of Agamosjnrura muscarum n sp. 

 (Text-figures 9-15). 

 The early stages are found encysted in the abdomen of 

 the fly. The smallest embrj-o met with measured 610 fi 

 in length by 50 to 60 /a in breadth (fig. 9-13). The mouth 

 led into a shallow pharynx 8 ^ in depth, followed by a 

 short thick oesophagus, the distance of its base from the 

 oral opening being 120 jn. A nerve ring surrounded the 

 oesophagus at a distance of 65 jli from the mouth. The 

 intestine was a long straight tube leading into a rather 

 large rectum 75 ft in length. An anal operculum was present. 



