190 The American Naturalist. [February, 
pottery, I am convinced from the charcoal and other indications that 
these remains are of human origin and I am thus able to make known 
for the first time the existence of the true shell mound in Peru. That 
these mounds are mere heaps of loose shells rather than compact mas- 
ses, as in Florida, and other places is no argument against their great 
antiquity, for in the practically rainless desert region in which they 
are found they might easily have remained unchanged for many ages. 
Before attempting to draw any conclusions from the data afforded us 
by the different classes of remains which exist in this locality about 
the Chira Valley, it will be necessary ta take a brief survey of what is 
known of its history. We have but one authority on this subject, 
Garcilasso de la Vega, and although his account is far from being a 
model of either history or chronology, it is certainly based upon tradi- 
tion and is therefore full of suggestion. When the Incas set out to 
conquer the coast valleys they found them occupied by a warlike and 
well advanced race called the Yuncas, whose chief centre of power ex- 
tended from the Chincha Valley near the modern Pisco, to the great 
Chimu at Trujillo while their dominion reached over all the surround- 
ing tribes. According to their own legends these Yuncas were of for- 
eign origin, and their ancestors, after affecting a landing in Peru, had 
through sheer innate superiority conquered their barbaric neighbors, 
and laid the foundations of the great nation which in time grew to the 
proportions in which the Incas found it. After subduing the Yuncas, 
the Incas proceeded northward and in the remote valleys of that region 
encountered a people of so low a condition, so poor and bestial that it 
was necessary to compel them to pay tribute in lice in the hope of 
teaching them the rudimentary principles of cleanliness. The Chira 
was one of these outlying valleys, but the millions ‘of graves which it 
contains and the high civilization which they reveal, prove at once the 
chronological inaccuracy at least of de la Vega’s story. It is probable 
that his errors arose from confusing Incan and Yuncan traditions, and 
that it was the Yuncas and not the Incas who came in contact with the 
barbarians. . 
It is hardly possible to suppose that the people of the shell mounds 
could ever have risen through their own efforts to so high a level as 
was obtained by the inhabitants of the Chira; it is even improbable 
that they could have done so with the aid of extraneous influence. A 
more likely theory is available. Before the coming of the Y uncas, a 
shell mound tribe occupied the desert adjacent to the mouth of the 
Chira and were either exterminated by invaders or had ceased to exist 
before their arrival. After the manner of all semi-civilized or semi- 
