378 AFRICAN GAME TRAILS 



well marked; but there are some curious differences between 

 the zones on these equatorial African snow mountains and 

 those on similar mountains in the northern hemisphere, 

 especially America. In the high mountains of North Amer- 

 ica the mammals are apt to be, at least in part, of totally 

 different kinds from those found in the adjacent warm 

 or hot plains, because they represent a fauna which was 

 once spread over the land, but which has retreated north- 

 ward, leaving faunal islands on the summits of the taller 

 mountains. In this part of Africa, however, there has been 

 no faunal retreat of this type, no survivals on the peaks of 

 an ancient fauna which in the plains and valleys has been 

 replaced by another fauna; here the mammals of the high 

 mountains and table-lands are merely modified forms of 

 the mammals of the adjacent lowlands, which have grad- 

 ually crept up the slopes, changing in the process. High 

 on Mount Kenia, for instance, are hyraxes, living among 

 the snow-fields, much bigger than their brethren of the 

 forests and rocky hills below; and light-colored mole rats, 

 also much bigger than those of the lower country. More- 

 over, the lack of seasonal change is probably accountable 

 for differences in the way that the tree zones are delimited. 

 The mountain conifers of America are huge trees on the 

 middle slopes, but higher up gradually dwindle into a thick, 

 low scrub, composed of sprawling, dwarfed individuals of 

 the same species. On Mount Kenia the tree zone ceases 

 much more abruptly and with much less individual change 

 among the different kinds of trees. Above this zone are the 

 wet, cold downs and moors, with a very peculiar vegeta- 

 tion, plants which we know only as small flowering things 

 having become trees. The giant groundsell, for instance, 

 reaches a height of twenty feet, with very thick trunk and 

 limbs which, though hollow, make good firewood; and this 

 is only one example of the kind. 



At Nairobi we learned, as usual, of incident after inci- 

 dent, which had happened among our friends and ac- 

 quaintances, of exactly the type which would occur were 



