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at first sight seems a not very large census; and no doubt in time 
and under very favourable circumstances it will be to some extent 
increased. Every naturalist who resides for some time even in a 
good collecting district knows how long a time it takes to arrive 
at a complete census of the groups of its fauna in which he is 
especially interested; and how his experiences vary from year to 
year and from season to season. Still less is it likely that the 
zoological resources of an enormous area like Central Australia 
should be exhausted at a single attempt by visiting naturalists 
almost constantly on the move, however enthusiastic and assiduous 
they might be. From the experiences of Prof. Spencer we gather 
that if a zoological collector in Central Australia is to be success- 
ful in getting together a collection — not merely of skins of beasts 
and birds — but one at all representative of the general fauna, 
questions of time and patience must be of quite secondary import- 
ance. First of all he has to catch his animals — but in some 
seasons, and in the case of some of the most interesting members 
of the fauna, this is an unusually difficult task, and may entail 
long and patient waiting upon the rains, as well as securing the 
cooperation of the Aborigines. Should he arrive in a dry season 
he might without previous experience even wonder whether, 
except ants, there were any animals to be caught. The visit of 
the Horn Expedition was made during the winter months (May* 
Aug.) after good rains. But during the course of the expedition 
the rain kept off, the result being that a number of forms were 
overlooked, and many experiences were missed, and would have 
been missed altogether, had not Professor Spencer on his own 
account subsequently made a rapid supplementary journey to 
Charlotte Waters in time to see some of the more important but 
transient aspects of the transformation scene which the advent of 
good rains brings about. 
Looking at the Larapintine fauna as a whole, we find it 
characterised by both negative and positive features. The 
negative characteristics are shown by the absence of many widely 
distributed Australian forms, or among the higher groups by the 
limited number of species of the types which do occur, or by the 
