176 FISHES OF WESTERN SOUTH AMERICA 
specimen with 3, four with 4, two with 5, and one with 6 plates in front of the 
adipose; snout longer than the rest of the head; interorbital 2.0 to 2.3 in the head; 
eye 4.0-4.5 in the head; preorbital about two in its distance from the edge of the 
~ 
. ee 
Fie. 21. A natural bait. A termites’ nest cut open with ma- 
chete. Such nests, found in most sections of the tropical lowlands 
above the level of inundation, afford a convenient means of learning 
whether a pool contains fish. Pieces of the nest, crumbled into the 
water with their termite larvae, are a great attraction to them. 
The inhabitants of Loreto often feed their chickens the same con- 
venient protein food. 
lip; occipital process tapering, its margin concave; humeral plates in contact for 
most of their length in the largest, a less distance in the smaller; barbels reaching 
gill-openings; dorsal spine about 1.5 in the head; pectoral spine longer, equal to 
