424 TRANSACTIONS OF SECTION D. 
feeder in the larval state. Now its carrion-breeding habits have made it the 
most serious pest among all the blow-flies, for at the time when the wool on the 
sheep is too hot to breed maggots (in midsummer), and the other species are 
seldom seen, Calliphora rufifacies is laying her eggs on dead sheep and any offal 
found round the tanks and dams, and is thus always on the increase. At the 
present time (1914) this species seems to have taken the place of the two common 
house species, and to be responsible for the greater part of the damage, all over 
the interior, caused by the sheep-maggot-flies. 
The last species to attack our sheep, and that only within the last two years, 
is the introduced British sheep-fly (Zucilia sericata), a series that is the 
common ‘ green-bottle-fly’ about the coastal country. In this case we have the 
descendants of the introduced British sheep-fly after having lost the peculiar 
habit of its ancestors, again acquiring the taste from the habit of allied 
Australian blow-flies. 
8. Australian Trematodes and Cestodes: a Preliminary Study in 
Zoogeograhy. By 8. J. Jonnstron, B.A., D.Sc. 
Practically all the groups of vertebrate animals found living in the various 
zoogeographical regions of the earth harbour numbers of parasitic worms. The 
entozoan fauna of one of these classes of vertebrate host in any particular 
region is constituted by a number of species which are found to be related to 
others which comprise the entozoan fauna of the same class of vertebrate host 
living in some other region. For instance, the entozoan fauna of marsupials in 
Australia comprises a number of Cestodes (e.g., species of Zinstowia) and a 
number of Trematodes (e.g., species of Harmostomunv), and the nearest relatives 
of each of these are found in certain species of Linstowia and Harmostomum 
that live parasitic in South American marsupials. 
The Trematodes and Cestodes of Australian birds find their nearest relatives 
in worms living in related birds that inhabit other parts of the world; and the 
Trematodes and Cestodes of Australian frogs are most closely related to those of 
frogs in other regions. 
The entozoan fauna of the host-animals belonging to any particular class of 
vertebrate may be separated into two divisions :—(1) Those that have been 
parasitic in these hosts for a very long time—practically from the first appear- 
ance of the host-animals, and (2) those that represent more recent acquirements. 
The members of the former division may be readily recognised by the fact that 
they have near relatives parasitic in other branches of the same stock, whilst 
members of the latter division generally have not. The members of each genus 
(or sometimes of several closely related genera) in the former division, in many 
cases scattered all over the world, constitute a natural group, and must be 
looked upon as derived from common ancestors. 
These ancestors were parasites of the progenitors of the host-animals in the 
very early days, when the group was much younger and much more restricted in 
its distribution than at the present time. A study of the relationships and 
distribution of the parasites affords some circumstantial evidence of the past 
movements and paths of dispersal of the host-animals. 
9. On the Emergence of the Nymph of Anax papuensis (Burm) from 
the Hgg (Class Insecta, Order Odonata). By R. J. Tinuyarp, 
M.A., F.E.S. 
Previous to hatching, the embryo lies with its head fitting closely under the 
pedicel or cap of the egg. The eyes are large and blackish, the antenne lying 
between them and directed posteriorly. The clypeus, labrum, mandibles, and 
maxilla can be clearly seen. The labium appears as a large paired organ directed 
posteriorly, and reaching well down between the legs. The legs lie directed 
posteriorly along the outer (ventral) surface of the embryo, except the hind tarsi, 
which are directed forwards. The hind end of the abdomen is bent round the 
posterior end of the egg, the ninth and tenth segments, with the cerci, being 
directed forwards. The mid-gut still encloses a large cylinder of yolk. The 
tracheal system can be seen, but is devoid of air, 
