Chap. I. 
SANDY BEACHES. 
35 
and it did not, for some time occur to us to consult our 
little companion, who had been playing with his bow 
and arrow all the way whilst we were hunting, ap- 
parently taking no note of the route. When asked, 
however, he pointed out, in a moment, the right direc- 
tion of our canoe. He could not explain how he knew ; 
I believe he had noted the course we had taken almost 
unconsciously : the sense of locality in his case seemed 
instinctive. 
The Monedula signata is a good friend to travellers 
in those parts of the Amazons which are infested with 
the blood-thirsty Motuca. I first noticed its habit of 
preying on this fly one day when we landed to make 
our fire and dine on the borders of the forest adjoining 
a sand-bank. The insect is as large as a hornet, and has 
a most waspish appearance. I was rather startled when 
one out of the flock which was hovering about us flew 
straight at my face : it had espied a Motuca on my neck 
and was thus pouncing upon it. It seizes the fly not 
with its mandibles but with its fore and middle feet, and 
carries it off tightly held to its breast. Wherever the 
traveller lands on the Upper Amazons in the neigh- 
bourhood of a sand-bank he is sure to be attended by 
one or more of these useful vermin-killers. 
The bay of Mapiri was the limit of my day excur- 
sions by the river-side to the west of Santarem. A 
person may travel, however, on foot, as Indians fre- 
quently do, in the dry season for fifty or sixty miles 
along the broad clean sandy beaches of the Tapajos. 
The only obstacles are the rivulets, most of which are 
D 2 
