ECOLOGICAL loi 



a rodent, whereas a mole belongs to the distant order of Insectivores. 

 In Spalax the body is barrel-like ; there is little in the way of tail or 

 ear-trumpets, the strong limbs are fossorial, the eyes are small and 

 may be degenerate, as in Spalax typhlus^ sometimes called the blind 

 mole-rat. In winter the Spalax burrows deeper, below the grip of 

 the frost's fingers, and feeds on roots and bulbs, which it sometimes 

 stores. Here, then, is a clear-cut instance of successful adaptation 

 to difficult conditions, for Spalax conquers the steppe by becoming 

 a creature of the underworld. The same may be said of many other 

 burrowing rodents, such as the gregarious sousliks that make great 

 warrens and often baulk man's efforts at steppe-conquest by 

 devouring the crops in the fields he has ventured. 



The subterranean mode of life is also illustrated by marmots, 

 hamsters, and voles; and it is said that our hedgehog, which we do 

 not count as a burrower, though it may shelter in rabbit-holes, 

 sometimes digs on the other side of the Caspian to a depth of eight 

 or nine feet — an interesting variation in habit. Perhaps to be included 

 are several species of Pika or Piping Hares, with short vole-like 

 ears, no external tail, and a peculiar call. We say "perhaps", because 

 most of them resemble our Variable Hare in preferring the uplands, 

 and some resemble marmots in living at very high altitudes. 



A second solution of the steppe problem is beautifully illustrated 

 by the biped Jerboas, such as Alaclaga jaculus, badly called the 

 Jumping Rabbit, and the fascinating Dipus hirtipes, whose tail 

 (7 inches) is longer than its body {^\ inches). Their particular 

 solution is that they have added to burrowing an extraordinary 

 elusiveness. They take prodigious unpredictable jumps, landing 

 neatly on their three-toed feet, the fore-limbs being held tightly 

 against their breast. We can understand the very long and springy 

 hind-legs, the long coalesced instep bones, the very long balancing 

 tail, and so on ; but we do not know how to interpret the fusion of 

 five or six neck vertebrae. The atlas or first vertebra is always free, 

 and sometimes the last; five are always fused. There is no clue in 

 the fact that a similar coalescence occurs in whales ! 



Brehm describes the nocturnal jerboa with his usual enthusiasm. 

 "After sunset, or later, if the moon be favourable, one may see the 

 charming creature steal cautiously from his hole. He stretches 

 himself, and then, with his little fore-limbs pressed close to his 

 breast, hops off on his kangaroo-like hind-legs, going as if on stilts, 

 balancing his slim, erect body by help of his long hair-fringed tail. 

 Jerkily and not very rapidly the jerboa jumps along the ground., 

 resting here and there for a moment, sniffing at things and touching 

 them with his long whisker-hairs, as he seeks for suitable food." 

 He eats what he can get — seeds, bulbs, smaller mammals, and birds' 

 eggs. When all is quiet he hops about in a leisurely way; but on the 

 appearance of an enemy, such as wolf, fox, eagle, or man, he puts 



