president's address. 661 
complete or almost complete absence of representatives of orders 
which are abundant in other parts of the continent. This state 
of things is sufficiently accounted for by the arid nature of the 
country and its unsuitability for their maintenance, or by the 
effectual climatic barrier which keeps them out. Thus, it would 
seem that with the want of suitable perennial rivers and creeks 
may be correlated the absence of Platypus, just as the absence of 
forests accords with a dearth of arboreal Phalangers. Land 
Planarians, Peripatus, Terrestrial Amphipods and Isopods, and 
Slugs are among the other notable absentees (as well as Myrio- 
pods — possibly an unintentional omission). 
Earthworms are poorly represented, only one species having 
been found. This — a species of Acanthodrilus — is a treasure 
which in quality compensates for some of the deficiency in 
quantity. It is a good instance of discontinuous distribution, 
and furnishes Professor Spencer with an opening for some 
interesting speculations. The genus is one which in Australia 
has lost ground, being at present but feebly represented in a few 
widely separated localities. Formerly when the rainfall was 
greater it was probably the dominant genus in the northern 
portion of the Continent, as it still is in jSTew Zealand and 
elsewhere in the Southern Hemisphere. 
Butterflies and Lepidoptera generally are not numerously 
represented. But the collection was made during the winter 
months, or rather during a dry spell, which will perhaps to 
some extent account for the scarcity. 
The positive characters are shown chiefly in this — that the 
Larapintine fauna is a select assemblage of species which may 
perhaps be roughly classified as very hardy species, and as species 
which in habit or in structure have become specially adapted to 
live in an arid region, or which have been able to take advantage 
of some favourable external circumstances. 
Some of them doubtless are the lineal descendants of forms 
which have uninterruptedly inhabited the region from a time 
antecedent to the setting in of the Dry Period, which proved so 
disastrous a change to forms like the Diprotodon. Others are 
