240 
too, as the water, running in torrents from their sides, carried down 
much gravel. It was evidently a landformation not very apt to lodge 
a freshwater fauna of any importance. It is difficult to ascertain 
whether elements of this fauna still survive in the present fauna. 
This might possibly be the case with Aplocheilus celebensis M. Wes. 
and Anabas scandens Dawp., which form a special element in the present 
fauna. One of these, Aplocheilus belongs to the family Poecilidae, 
several genera of which are known from the early tertiary; and 
Anabas scandens has a very wide range of distribution, from the 
continent of Asia to the eastern part of the indo australian archipelago. 
The recent fishfauna only came to full development when Timor was 
raised to its present level in post pleistoceen times. This very young 
land developed a system of rivers, which could only be populated 
by such fishes, as are not hindered by salt water in their distribution. 
Timor, when rising, was surrounded by sea. The ichthyological 
material tends to prove that this was originally a shallow sea, possibly 
surrounding other greater or smaller islands in the neighbourhood, 
as, for several elements of the freshwaterfauna of Timor, a deep sea 
with a high salinity would form an unsurmountable barrier. Such 
a sea could only have been formed after the immigration in the 
freshwater was accomplished for the greater part. 
We are of opinion that this is in accordance with the views 
of MoreNeraarr, who thinks that the formation of the deep seas 
along the north and south coast of Timor took place in connection 
with the final upheaval of the island, and that this has been the 
latest event. 
Physics. — “On the Deduction of the Equation of State from Boraz- 
MANN’s Entropy Principle.’ By Dr. W. H. Krrsom. Supplement 
No. 24a to the Communications from the Physical Laboratory 
at Leiden. (Communicated by Prof. H. KAMERLINGH ONNES). 
(Communicated in the meeting of April 26, 1912). 
$1. Introduction. Since the two great advances made by vaN 
per Waats in deducing his equation and in developing the theory 
of corresponding states therefrom, the theoretical investigation of the 
equation of state for a single component substance has been developed 
in various directions, particularly by van DER Waats himself; these 
developments have cleared up and enriched our knowledge of various 
circumstances which influence the equation of state, and which had 
