As compared with its reptilian associates in northeastern Kansas, _Eumeces fasciatus_ is outstanding in its ability to become active and carry on normal activities at relatively low air temperatures. In spring it is usually seen in the open before any other kind of reptile, because it has the capacity to move about sluggishly at temperatures so low that some other reptiles are numbed and completely immobilized, and because it has small size enabling it to make rapid adjustment upward by insolation, or contact with sunshine-warmed surfaces. By virtue of this ability it has been able to extend its range farther northward than most other reptiles, and it has gained the advantage of a longer growing season. This advantage was especially apparent in the spring of 1953. A mid-March warm spell with seven out of eight successive days having maximum temperatures in the sixties culminated on March 20, with a maximum air temperature of 82°F. This warmth was sufficient to activate most of the five-lined skinks, and a few reptiles of other kinds. After the unseasonably high temperature of March 20, there was rapid return to cooler weather with temperatures frequently below normal throughout April. As a result there was little activity of other kinds of reptiles that month, but five-lined skinks were active on most days. On only a few days, those with temperatures in the low forties or those on which the sky remained overcast, did the skinks remain inactive. On most days maximum temperatures were in the fifties and sky was clear. Under these conditions the skinks were able to emerge and bask, rapidly raising their body temperatures far above those of the air and substrate. By the end of April some kinds of deciduous trees have not yet begun to leaf out, and in most other kinds the leaves are still in an early stage of development. Absence of a leaf canopy during April permits the skinks to utilize the spring sunshine to maintain their body temperatures at almost the same high level that they maintain in the same situations in hot summer weather. Table 2. Temperatures (in Degrees Centigrade) of Skinks Found Under Flat Rocks Exposed to Sunshine, Contrasted With Air Temperatures; Spring of 1953.