COMMUNITIES IN OTHER INLAND WATERS 375 



which are otherwise limited to warmer regions (Spain, north Africa), 

 have found refuge in Hungarian and Italian thermal waters. The 

 small annelid Aeolosoma quaternarium has been found in a number 

 of Italian thermal springs up to 40°. A few crustaceans such as 

 Palaemonetes varians are present as dwarf forms in Abbano, and a 

 few ostracods also occur in thermal waters. Water beetles are relatively 

 most plentiful; 8 species, some in large numbers of individuals, occur 

 in the thermal waters of Valdieri and Vinadio in northern Italy. 

 Brues 49 reports that, in the hot springs of the western United States, 

 a population of 51 species at 32.5° falls steadily to one of only 2 

 species at 45.5°. Saussure found eels in the basins of Aix at 46°, and 

 the minnow, Leuciscus thermalis, is said to live even at 50° in the 

 springs of Trincomaly. It is noticeable that the fauna of thermal waters 

 in general is made up of the same groups of animals as that of the 

 salt waters. Brues reports that at only one place in the world has it 

 been possible to follow the changes in composition of the thermal 

 fauna over a considerable range in water from a single source. This 

 has been done at the thermal springs of Meskhoutine, or Hammam 

 Meskhoutine, in northern Africa. 50 These springs are of very large size, 

 yielding between 400 and 500 gallons of water per minute or about 

 100,000 liters per hour at a high temperature between 78° and 95°. 

 Descending the stream arising from these springs to where the water 

 has cooled to 60° one finds dark green algae, but no animal life. At 

 51° the crustacean Cypris balnearia first appears. At 45° this Cypris 

 becomes very abundant and frogs jump into the water when disturbed, 

 but do not remain there voluntarily. At 44° Cypris is still abundant, 

 while the fresh-water crab, Telphusa fluviatilis, and tadpoles of Rana 

 esculenta appear. Adult frogs are numerous and are readily made to 

 enter the water, where they remain for extended periods. At 43° Cypris 

 becomes more rare ; annelids of the genus Ndis appear while frogs and 

 their tadpoles remain abundant. At 39° the Cypris has disappeared 

 and, according to Blanchard, 51 it occurs only between 43° and 51°. 

 Below this temperature the fauna gradually becomes normal. 



From Blanchard's observations there is no doubt that Cypris 

 balnearia is restricted to a definite range of temperatures above 40°. 

 To this may be added also the acarine genus Thermacarus with 2 

 species, one from eastern Asia and another from the western United 

 States, both found only in hot springs ; they represent the only known 

 species of a genus which constitutes by itself a distinct family of 

 hvdracarine mites. 



