JAN 26 1897 
ARCHIV FOR MATHEMATIK OG NATURVIDENSKAB. B. XIX Nr. 1. 
Introduction. 
Mr. Knut Dahl, who has been travelling for 2 years in 
the northern and western parts of Australia, and who also 
made some excursions into the interior of the continent, 
brought with him, on returning home this year, a sample 
of dried material taken by him from shallow depressions in 
the sandy desert, at a distance of about 40 miles east of 
Roebuck Bay. When he first visited these inner tracts, 
immediately after the rainy season, all the greater depres- 
sions were filled with rain-water, and swarmed with Ento- 
mostraca, among which an Apus was observed in great 
numbers. Unfortunately he did not preserve any of the spe- 
cimens, apparently owing to the want of a suitable preserving 
fluid. Later in the season he again visited the interior 
of the country, but now nearly all the depressions were 
completely dried up, and the whole country had the character 
of a barren desert. Having, however, learned that at 
times some parts of this desert were peopled by multitudes 
of small crustaceans, and knowing of the good results of 
my earlier hatching experiments, he kindly collected for 
my use some dried material from places where it was 
supposed that, at an earlier time of the season, rain-water 
accumulated. The material, when received (on the 4th May 
of the present year), had the character of a very fine, reddish 
1 — Archiy for Math. og Naturv. B. XIX. Nr. 1. 
Trykt den 2ide Oktober 1896. 
