60 



Proceedings of the Royal Society of Victoria. 



Lizards, Average Weight, 330 Grams. 



Similar tables might be made out for fish, for turtles, for 

 snakes, and all the cold-blooded animals, showing that they take 

 their temperature absolutely from the media in which they exist, 

 and when it is found that they do not exactly coincide with it, 

 the cause is generally to be found in the fact that for a rising or 

 falling temperature of the medium the animal will not at once 

 respond to the change ; it lags behind and will in a cooling 

 medium be warmer, in a warming medium cooler than its sur- 

 roundings. Occasionally, however, a slight excess of heat is due 

 to the animal's activity. 



Cyclodus gigas is a very sluggish creature, and if left alone never 

 warms himself by any exertion, yet if one takes his temperature 

 in the early part of the day it will almost always be found to be 

 below that of the air. After sunset, it is generally higher. 

 During two years I kept specimens of this species in a box, some- 

 times six or eight, sometimes only two or three. I took their 

 temperatures morning and evening, not altogether continuously, 

 but throughout the larger portion of that time. The average of 

 all these observations gave for lizards 181°, for the air 18"4°. 

 This is a very close approximation considering that the tempera- 

 tures had the wide range that lies between 12° and 32°. The 

 lizards appear to be colder a little than the air. This I believe to 

 be clue only to the fact that, taking temperatures before eight 

 o'clock in the morning, the lizards were still considerably in the 



