140 THE WONDER OF LIFE 



Another series of strange habitats has been found in the 

 burrows made by moles and hamsters and other mammals 

 of similar habit. There are, of course, accidental co- 

 tenants ; and there are others which though often found in 

 burrows occur elsewhere as well ; and there are parasites 

 belonging to the burrowing mammals. But after these 

 are taken account of there remains a distinct burrow-fauna, 

 just as there is a distinct cavern-fauna. Thus L. Falcoz 

 mentions the Staphylinid beetles, Heterops prcevia, 

 Oxypoda longipes, and Aleochara spadicea as good illus- 

 trations of the fauna of moles' nests. 



Many beetles visit nests casually for pickings ; others 

 are frequenters of nests but of other suitable places as 

 well ; there is a third lot of exclusively ' nidicolous ' 

 Coleoptera, and the list of these drawn up by Bickhardt 

 in 1911 came to twenty-eight. Eighteen of these are 

 confined to the homes of mammals, such as mole, hamster, 

 mouse, and rabbit ; seven are confined to the nests of 

 birds, such as dove, sand-martin, owl, and woodpecker ; 

 three are found associated with both birds and mammals. 



A curious refuge is that of the rare sea-otter on the 

 great beds of kelp seaweed (Macrocystis) which fringe the 

 rocky coast of the North Pacific, among the Aleutian and 

 Kurile Islands. We read that ' these great kelp beds 

 make calm water, though the surf be roaring and breaking 

 just outside, and are dense enough for the otters to lie 

 upon.' In the middle of the nineteenth century the sea- 

 otter was still comparatively plentiful all round the North 

 Pacific coast, now it is hardly to be seen even by the 

 exploring naturalist. It is interesting in its adaptations 

 for aquatic life the hind feet being suited only for swim- 

 ming ; in the adaptation of its back teeth for crunching crabs, 



