134 TROPICAL SAVANAS 
Among the various mole-like forms of Africa mention 
may be made of the little sand-rats (Heterocephalus) 
of the sandy deserts of Somaliland. These little animals 
—which are no bigger than a mouse—are nearly naked, 
perhaps as an adaptation to life in sandy soil. They 
resemble moles in having no external ears, and in their 
almost functionless eyes. 
Of the rodents of South America the majority have a 
wide distribution, ranging from the true savanas south- 
ward to the pampas of the Argentine and the plains of 
Patagonia. The viscacha (Lagostomus trichodactylus), 
according to Mr. W. H. Hudson the most typical 
inhabitant of the pampas, extends beyond their limits, 
though scarcely into the savanas proper. On the 
other hand the mole-like tucotucos (Ctenomys) are 
burrowing animals, which occupy sandy regions from 
Brazil and Bolivia to the extreme south. The coypu 
(Myopotamus), an aquatic form haunting the banks of 
rivers and lakes, has an even wider distribution. Many 
species of cavy also occur, some being partial to moist 
situations, while others dwell in rocky regions. The 
largest living rodent, the capivara or capybara (Hydro- 
choerus capivara) has a very wide distribution, and is 
aquatic in its habits, frequenting the margins of lakes 
and rivers, but also feeding on the open plains. 
Of the South American Edentates most of the arma- 
dillos inhabit open country within the tropics, though 
some extend into extra-tropical regions. Most prefer 
arid regions, and feed on insects and carrion, together 
with some vegetable matter. The tiny pichiciago or 
fairy armadillo (Chlamydophorus) is found in sandy 
regions in the western part of the Argentine where the 
vegetation consists of cactuses and thorny brushwood. 
It burrows with great rapidity, and is very sensitive 
