Biography of the Vrzcacha. 297 
dry mound of soft earth which the vizcacha elevates 
amidst a waste of humid, close-growing grass is not 
absolutely necessary to the existence of all these 
species, it supplies them with at least one favourable 
condition, and without doubt thereby greatly in- 
creases their numbers: they, also, whether preda- 
cious or preyed on, have so many relations with 
other outside species, and these again with still 
others, that it would be no mere fancy to say that 
probably hundreds of species are either directly or 
indirectly affected in their struggle for existence by 
the vizcacheras so abundantly sprinkled over the 
pampas. 
In winter the vizcachas seldom leave their bur- 
rows till dark, but in summer come out before 
sunset ; and the vizcachera is then a truly interest- 
ing spectacle. Usually one of the old males first 
appears, and sits on some prominent place on the 
mound, apparently in no haste to begin his evening 
meal. When approached from the front he stirs 
not, but eyes the intruder with a bold indifferent 
stare. If the person passes to one side, he deigns 
not to.turn his head. 
Other vizecachas soon begin to appear, each one 
quietly taking up his station at his burrow’s mouth, 
the females, known by their greatly inferior size 
and lighter grey colour, sitting upright on their 
haunches, as if to command a better view, and in- 
dicating by divers sounds and gestures that fear and 
curiosity struggles in them for mastery; for they 
are always wilder and sprighther in their motions 
than the males. With eyes fixed on the intruder, 
at intervals they dodge the head, emitting at the 
