4 The Naturalist in La Plata. 
and grace it possessed, it might not seem inoppor- 
tune at the present moment to give a rapid sketch, 
from the field naturalist’s point of view, of the great 
plain, as it existed before the agencies introduced 
by European colonists had done their work, and as 
it still exists in its remoter parts. 
The humid, grassy, pampean country extends, 
roughly speaking, half-way from the Atlantic Ocean 
and the Plata and Parana rivers to the Andes, and 
passes gradually into the ‘“‘ Monte Formation,” or 
sterile pampa—a sandy, more or less barren district, 
producing a dry, harsh, ligneous vegetation, princi- 
pally thorny bushes and low trees, of which the 
chatiar (Gurliaca decorticans) is the most common ; 
hence the name of ‘‘ Chaiiar-steppe’’ used by some 
writers: and this formation extends southwards 
down into Patagonia. Scientists have not yet been 
able to explain why the pampas, with a humid 
climate, and a soil exceedingly rich, have produced 
nothing but grass, while the dry, sterile territories 
on their north, west, and south borders have an 
arborescent vegetation. Darwin’s conjecture that 
the extreme violence of the pampevo, or south-west 
wind, prevented trees from growing, is now proved 
to have been ill-founded since the imtroduction of 
the Eucalyptus globulus; for this noble tree attains 
to an extraordinary height on the pampas, and 
exhibits there a luxuriance of foliage never seen in 
Australia. 
To this level area—my “parish of Selborne,”’ or, 
at all events, a goodly portion of it—with the sea. 
on one hand, and on the other the practically 
infinite expanse of grassy desert—another sea, not 
