88 ZOOLOGICAL SKETCHES. 



keys often tease him, or by their indiscreet chattering 

 betray his whereabouts with all the schadenfreude 

 " mischief-joy" of blabbing school-boys. Even birds 

 join in that heartless sport. The discovery of a sloth 

 seems to excite them like the aspect of a blinking owl. 

 A tardo is as lean as a monkey; the sharpest teeth 

 could not pick more than twelve ounces of meat from 

 his bones ; but for the sake of those twelve ounces the 

 South-American variety is unmercifully hunted by the 

 Brazilian plantation-slaves, who have to eke out their 

 meat-rations with tortoise-eggs and such game as they 

 can procure without fire-arms. 



No enemy, however, can catch the sloth napping; his 

 is a sleepless soul ; his inert brain requires no rest. 

 Heat and cold do not affect his sensorium ; you may see 

 him hang on to a top branch under the glare of a vertical 

 sun, eating placidly, listless and mute, like a survivor 

 of the antediluvian fauna, the age of sluggish monsters, 

 when Professor Owen's sloth-like megatheriums pastured 

 the fern-forests of the tertiary period. 



But if his physical organization classes the sloth with 

 the lowest mammals, his mental calibre degrades him 

 below the rank of a first-class reptile. There is a small 

 Peruvian variety of arboreal tardigrades, the unau, or 

 spotted sloth, whose habits in captivity I had no oppor- 

 tunity to observe ; but in the brain of the tardo real, the 

 large dark-brown sloth of Mexico and Central America, 

 the faculties which distinguish the average mammal from 



