JOHANSEN 



together with the edentates (Xenarthra) , others with the insecti- 

 vores, and still others at the base of the ungulate stock. Unfor- 

 tunately for us, nothing has been done yet with this unique repre- 

 sentative of the primitive placental mammals. 



Representatives of the Old World's scaly anteaters have like- 

 wise scarcely been subjected to study in regard to their tempera- 

 ture regulating ability. Eisentraut (1956b^ reports a body tempera- 

 ture range for Manis tricuspis from 32.2 C to 35.2 C. A similarly 

 limited number of observations is available on the tropical anteaters 

 from Central America. WislocM and Enders (1935) report that the 

 giant anteater ( Myrmecophaga jubata ) shows a rectal temperature 

 between 32° C and 34 C at air temperatures between 16 C and 

 21° C. The three- toed anteater ( T am andua tetradactyla ) shows rec- 

 tal temperatures between 33.7 C and 34.6 ^C at air temperatures 

 between 25° C and 27.6° C. The more sluggish two- toed anteater 

 (Cyclopes didactylas) displayed a lower level of body temperature 

 between 28^.9'' C and 31.3 C and showed a greater variance during 

 exercise than the other two species. Enders and Davis (1936) 

 recorded somewhat higher rectal temperatures on the T am andua 

 tetradactylum . They got 35.0° C to 35.7 C at an air temperature 

 of 27 C. The uniquely specialized group of sloths has been studied 

 by a number af workers. In 1924 Ozorio de Almeida and Branca 

 de A. Fialho observed a range from 30 C to 32.9 C at an air 

 temperature between 19 C and 25.8 C for the three-toed sloth 

 ( Bradypus griseus ). Kredel (1928) recorded a range from 27.7 C 

 to 36.8 C at air temperatures from 24.5 C to 32.4 C. Upon 

 exposure to a moderate cold stress, the three-toed sloth loses 

 considerable heat rapidly. According to Gibbs, cited by Wislocki 

 (1933), Bradypus griseus lost 8 C in deep rectal temperature, 

 dropping from 33 C to 25 C in 2 hours and 40 minutes when 

 transferred from an air temperature of 26 C to 13 C. Britton 

 and Atkinson (1938) often observed spontaneous variations in body 

 temperature of Bradypus with no apparent reason. In the light of 

 this it seems of interest that Irving et al. (1942) found that the 

 resting metabolism could be readily depressed, particularly in 

 relation to disturbances of the breathing pattern. The two-toed 

 sloth (Gholoepus hoffman ni) is more active than Bradypus and 



100 



