Along the Essequebo and Potaro. i 13 



the trees close by ; but an eager search with some of the 

 Indians yielded nothing. 



At the landing place here, our first perai (Scrrasalmo 

 niger) was caught on a hook. The throw had scarcely 

 been made, ere the voracious fish had taken the bait, 

 and had been landed grunting and fiercely snapping its 

 terrible jaws ; and doubtless it had been attracted by the 

 smell of a wounded cayman (Alligator niget ) which was 

 suspended from the stern of the boat, but quite out of 

 reach, above the water. This common species of perai, 

 apparently the most widely distributed in the colony. 

 with fiery reddish eyes and silvery sides, and with a pre- 

 vailing bluish-black tint over the rest of the body, was 

 the only one obtained on the trip, the largest individuals 

 attaining a length of about 12 to 16 inches. Its skin 

 was a most welcome one for the collection, since, hitherto, 

 it had been absent from the Museum set. 



The perais (Serrasalmo) are, in many features, closely 

 related to the salmon of the north temperate regions, 

 with which they were formerly classed; but they are 

 rendered very different in shape owing to the peculiar 

 flattening of the body from side to side, which renders it 

 very deep from front to back. The toothed or saw-like 

 ventral line, from which the technical name has been 

 taken, renders them also easily distinguishable Their 

 voracity, accompanied by a formidable armature of sharp 

 triangular teeth, set in strong, thick jaws, has given them 

 a wide reputation lor villainous biting, and one which is 

 easily understood when a lair specimen of their excising 

 power is under observation. 



The family of fresh-water fishes, the Characinida?, to 

 which the perai belongs, is peculiarly rich in species, and 



