ZOOLOGY. 273 



of species, which is known to have occurred in geological periods. 

 This is effected through the prevalence of an epidemic disease, which 

 apparently has its origin in the decomposition of vegetable detritus, at 

 or near the river's .head waters. Its ravages are thus described as 

 witnessed on the river Apure, in Venezuela : 



" The first symptoms of the epidemic appeared among the crocodiles, 

 whose hideous carcasses might then be seen floating down the stream 

 in such prodigious numbers, that both the waters and air of that fine 

 region were tainted with their effluvium. It was observed that they 

 were first seized with a violent fit of coughing, followed by a black 

 vomit which compelled them to quit their watery home, and finally find 

 a grave amongst the thickets on the river banks. The disease next 

 attacked the fish and other inhabitants of the water, with equal vio- 

 lence, until it was feared the streams would be depopulated. The fear- 

 ful mortality among them can be better estimated from the fact that, 

 for more than a month, the rippling waves of that noble river, the 

 Apure, were constantly washing down masses of putrefaction, its placid 

 surface being by them actually hidden from view for several weeks. 

 The next victims were the pachidermata of the swamps ; and it was a 

 pitiable sight to see the sluggish chigiiires (capyvaras), and the grizzly 

 wild-boars dragging their paralyzed hind-quarters after them ; hence 

 the name of derrengadera applied to this disease. Not even monkeys 

 in their aerial retreats escaped the contagion, and their melancholy 

 cries resounded day and night through the woods like wailings of the 

 eternally lost. It is a singular fact, that while the scourge did not 

 spare any of the countless droves of horses roaming the savannas of 

 the Apure and adjacent plains, donkeys, and horned cattle were seldom, 

 if ever attacked, so that, by their aid, the owners of cattle-farms were 

 enabled to prevent the entire dispersion of their herds." 



Some of the Venezuelian rivers are infested with a peculiarly fero- 

 cious and blood-thirsty fish known as the caribe, which, though not lar- 

 ger than a perch, is one of the most formidable creatures that man or 

 beast can have the misfortune to encounter. Their sharp, triangular 

 teeth, arranged in the same manner as those of the shark, are so 

 strong, that neither copper, steel, nor twine can withstand them, and 

 hence the angler stands no chance of sport where the caribe is found. 

 " The sight of any red substance," says Don Ramon, " blood especial- 

 ly, seems to rouse their sanguinary appetite ; and as they usually go 

 in swarms, it is extremely dangerous for man or beast to enter the 

 water with even a scratch upon their bodies. Horses wounded with 

 the spur are particularly exposed to their attacks, and so rapid is the 

 work of destruction, that unless immediate assistance is rendered, the 

 fish soon penetrate the abdomen of the animal, and speedily reduce it 

 to a skeleton." This cannibal fish is as beautiful in aspect as it is fierce 

 in nature. " Large spots of a brilliant orange hue cover a great por- 

 tion of its body, especially the belly, fins, and tail. Toward the back, 

 it is of a bluish-ash color, with a slight tint of olive-green, the inter- 

 mediate spaces being of a pearly white, while the gill-covers are tinged 

 with red." This fish, however, suffers from a special and constantly 

 recurring visitation ; being subject to a yearly mortality during the heat 

 of summer when the water is deprived of a portion of the air it holds 

 in solution. " Their carcasses," says Don Rayrnon, " may then be 



