358 MK. R. X. araTHER ON THE 



is a fair estimate of the density of tlie population. If it be 

 ;assumed that the average depth of the lake is 6 metres, the 

 total population, of the 1750 square miles of lake must be at least 

 39 X 10^- adult individuals. 



• The eggs of the Artemia may often be seen floating on the 

 surface in long, interlacing streaks of a brown colour. The 

 Artemias and their eggs are indubitably the food of the great 

 •concourse of water-fowl which have been remarked by all travellers 

 as dwelling on the shores of the lake. In August I saw no 

 flamingoes, although quantities of their pink feathers on the 

 beaches testified to their presence earlier in the year. Grulls 

 and ducks were very abundant. 



Influence of a Saline Environment. — It appears that although 

 the water of Lake Urmi is not incompatible with the well- 

 being of all organic life, yet its salinity is too great to admit of 

 the existence of more than a few species. They are on the whole 

 similar to the species described from other salt lakes in desert 

 regions, but the fauna is rather more limited. Lake TJrmi, in 

 respect of its fauna, is very similar to the Adschidarja, near the 

 Caspian Sea ; it does not contain so many species as the less saline 

 pools of the neighbourhood of Odessa {SchmmiTceivitsch), nor do 

 any Coleopterous insects appear to have become acclimatized to 

 its waters as has happened in certain American and European 

 salt waters. It is possible that a worm may yet be found living in 

 its waters, as PacJiydrilus does in the strong brine-springs of 

 Kissingen (^ewiper) and Kreuznach {Claparede) . The affinity of 

 the TJrmi fauna is undoubtedly with that of the fresh-water 

 rather than with that of the sea ; the fauna is therefore not to 

 be regarded as halolimnic in Mr. J. E. S. Moore's seui^^e of the 

 word : it is decidedly halophilous. 



The influence of a strong saline solution upon the struc- 

 ture and habits of au organism has engaged the attention 

 of several naturalists. The early researches of Plateau and 

 Beudant proved that many freshwater animals will live in sea- 

 water and vice versa, ^o long as the change from one to the other 

 De not effected too suddenly; and also that diff'erent animals 

 have different powers of resistance to such a change. In 1889 

 Boas * described the remarkable changes of structure which 

 occur in Faloemonetes varians in accordance witli its growth 

 in fresh or salt water. The last few years have produced 

 * Zool. Jahrb. iv. 



