188 MmMuUSCA AUSTRALIS MACQ., M. VETUSTISSIMA WALKER. 
which, though fresh, is naturally drier and harder. Thus: 
scores of flies will visit the former for larviposition in 
comparison with one or two visiting the latter. This 
instinct is of great value to a fly which has to contend 
with excessive heat and aridity. 
We have found M. australis breeding naturally only 
in cow and horse dung. Under experimental conditions, 
flies deposited larvae on wallaby dung and larvae reared. 
at first in cow manure, when transferred to wallaby faeces, 
bred out. We do not think that the pellets of wallaby 
dung under ordinary conditions serve as a suitable nidus, 
but when they become broken up and moistened with 
water, then, as we have observed, larvae can be reared to- 
maturity from such material. 
We have bred out specimens from bird excrement 
collected on the wet sand along the edge of the Burnett 
River, early larvae having first been transferred to a mass. 
of such material from cow manure. Fowlyard manure 
does not seem to offer a suitable nidus for M. australis, 
though M. domestica as well as blowflies visit it for ovi- 
or larviposition. 
As cattle and horses have been introduced into 
Australia, some other material than their manure must 
previously have served as the natural breeding place of 
M. australis as well as M. vetustissima. Probably it breeds. 
in decomposing vegetation, as the latter under the name 
of M. corvina has been reported to do. 
Genital system. The genitalia of the female differ 
from those of M. domestica and resemble those of M. bezz1 
described and figured by Patton and Cragg (1913, p. 140, 
and pl. xxx, fig. 2). Each ovary consists of a single 
ovariole ; the ovarioles functioning alternately in passing 
an ovum into the uterus or terminal portion of the common 
oviduct which is greatly enlarged in this species. The re- 
lationship of the various parts will be best understood by 
reference to fig. 12. The two conglobate glands or 
accessory copulatory vesicles are comparatively large while 
the accessory glands are relatively much shorter than those 
of M. domestica (Hewitt., p. 49, figs. 20, 21), being of about 
the same length as the three spermathecae. The latter 
