BY H. S. HALCRO WARDLAW. 257 



nitude and unevenness of the daily variation in the case of 

 Echidna are quite in keeping with the general behaviour of its 

 temperature. It must be remembered, too, that temperatures 

 were observed only at two times of the day, and these may not 

 have coincided with the extremes of variation of the animals' 

 temperatures. 



If one considers now the relation of a series of morning- or of 

 afternoon-temperatures to the corresponding temperatures of the 

 air, it will be found that the variations of the former sometimes 

 take place in the same direction as those of the latter, and at 

 other times in the opposite direction. The prevailing tendency 

 is, however, for the variations of the air-temperatures and of the 

 body-temperatures of the animals to be in the same direction, so 

 that there seems to be some connection between the two. This 

 view is further supported by the comparison of the mean autumn- 

 temperatures of Echidna No. 6, with the mean spring- and sum- 

 mer-temperatures of the same animal. The air-temperatures 

 during Autumn were considerably lower than those during 

 Spring and the beginning of Summer. The average temper- 

 atures of the animal were : Autumn, morning, 29*4°, afternoon, 

 32-1**; Spring and Summer, morning, SO'l", afternoon, 32-9"C. 

 Over these fairly long periods, then, higher temperatures of the 

 animal were, as a rule, associated with higher air- temperatures, 

 although the evidence of any causal connection between the two 

 is not very strong. It will be remembered, however, that the 

 average morning- and afternoon-temperatures of several animals 

 (Tables iii. and iv.) were slightly higher in Autumn than in 

 Spring. 



Summary. — (l).During the winter-months, the Echidnas under 

 observation hibernated intermittently, their temperatures ap- 

 proximating to those of the air during the periods of hibernation. 



(2). Outside of the periods of hibernation, these Echidnas 

 maintained a temperature which was fairly constant (30-33°C.), 

 although lower than that of other mammals. Echidna, therefore, 

 is a true homoiothermal animal. 



(3). The temperature of these Echidnas showed a daily varia- 

 tion, which seemed to be, to some extent, independent of the 

 variations of the external temperature. 



