132 THIRSTY ANIMALS 



or, in fact, do so at all to any great extent. They 

 drink sparingly, and can probably, by habit and practice, 

 go for longer periods without drinking than species 

 living in well-watered districts. But the absence of 

 any special provision for the internal storing of water, 

 except in the camels and some tortoises, seems to 

 indicate that this power of temporary abstinence is 

 only an acquired capacity. Nor is it often possible to 

 be certain that stores of water do not exist in ' deserts ' 

 stores perfectly well known to the animals, though not 

 to travellers. This is especially the case in rocky 

 deserts such as the Bayuda Desert, and that between 

 Suakin and Berber. Some of the correspondents of the 

 London daily papers who recently made the journey 

 from the advanced posts on the Nile to Suakin noted 

 as remarkable that, though they were in a desert, and 

 making forced marches from want of water, which, 

 when found, was as black as ink and almost undrink- 

 able, hares and gazelles swarmed. This is an almost 

 certain sign that this desert is not waterless. Count 

 Gleichen, when recrossing the Bayuda Desert from 

 Metemmeh, found real cisterns of water in one place 

 away from the ordinary track. A typical desert-bird, 

 which, like the gazelles, jerboas, and sand-lizards, has 

 even taken its colour from its environment, is the sand- 

 grouse. Yet Mr. Bryden states that the daily flight 

 of the sand-grouse, a species of exceedingly swift and 



