472 
president’s address. 
at considerable depths in the North Atlantic, since such an 
equable climate cannot there be found near the surface. 1 
Further, it has been noticed that the number of marine 
species living in fresh water increases as we approach the 
Equator, showing an apparent connection with the increasing 
uniformity of temperature. 2 In the Philippines, for example, 
the “ difference between the extreme monthly mean of the 
temperature of the air reaches at the utmost 7 C.” (Semper., p. 
43 1). Weber 3 found an extraordinary contrast to the European 
fresh-water fauna with regard to the Crustacea of the East 
Indies. In place of the usual northern forms of typical fresh- 
water Arthrostraca there were found a number of Isopoda 
belonging to typically marine genera, and the number of 
Decapoda was very large. 
On the other hand it has been objected by Pelseneer 1 that 
equally uniform conditions may be found in Polar climates, 
and that it is only in temperate regions that great fluctuations 
occur. But, even if the sea in Arctic regions maintains a fairly 
uniform temperature, it is obvious that marine animals cannot 
readily adapt themselves to existence in rivers and lakes which 
are frozen solid for a large part of the year. 
There may possibly be some intimate and obscure relation 
between temperature and salinity which may affect the question, 
since Schmankewitsch asserts that, in the case of Artemia, an 
excessive increase of salinity could be made tolerable by a 
decrease of temperature, and vice versa. So also Issel ° states 
that the adaptation of marine animals to fresh water is made 
easier by a higher temperature. This conclusion is, however, 
disputed by Pelseneer, Bert, and others, on the ground that at 
higher temperatures the tissues are more permeable, and that, 
therefore, cold regions should be the best from this point of 
view. 
A high temperature does not appear to be favourable in itself 
1. Semper, Animal Life, 1881, p. 136. 
2. Von. Martens. Areli. Naturg. XXIII. 1857, p. 199. 
3. Weber. Zool. Ergeb. einer Reise in Nieder. Ostiudien, II., 1892. 
4. Pelseneer, Bull. Acad. Roy. Belgique, 1905. 
5. Issel. Atti. Accad. Torino. XXXVI. 
