THE PINE-TREE LIZARD. 165 



individuals remained of a light color under all circumstances ; 

 others, that were dark when received, became light for brief 

 periods, but were very dark fully ninety-five per cent of the time 

 they were under observation. 



The long and broad glistening green markings upon each side 

 of the abdomen are equally variable, certainly not a distinction 

 of sex, as suggested by Le Conte and Say, and often absent for 

 weeks in specimens which occasionally exhibited them in all their 

 brilliancy. 



In no instance was there that prompt change of hue that we 

 see in the tree-toad {Hyla versicolor), and even more so in the 

 wood-frog (Rana sylvatica). The change in the latter is as abrupt 

 and complete as in certain fishes, and is particularly significant, 

 inasmuch as it is the only frog that needs protective coloring, 

 living as it does in woodland tracts, where it is exposed to an 

 abundance of enemies : and may it not be that, by its power to 

 adapt itself to the general color of the surroundings, it renders 

 itself inconspicuous to the insects upon which it preys ? If so, 

 the control over its color becomes doubly advantageous. 



Vision in the pine-tree lizard is apparently not very acute, 

 although the eyes are exceedingly bright, and, when coupled with 

 certain movements of the head, suggest considerable intelligence. 

 It was found very difficult to test their visual powers, although, 

 once captured, these lizards became extremely tame, patient, and 

 obedient, and I could only infer that the sense of sight was none 

 of the best from the fact that when held to a mosquito-frame in 

 a window, upon which house-flies were walking, they missed fully 

 one half of those at which they snapped ; and other lizards in con- 

 finement, but where every possible freedom of movement was 

 practicable, often made many attempts to capture flies before suc- 

 cess crowned their efforts. If, therefore, when at large, they 

 depended principally upon winged insects for subsistence, their 

 lives would indeed be laborious ones ; but insects of sluggish 

 movements, ants, and small spiders, are all freely partaken of. 

 My friend Mr. George Pine, of Trenton, N. J., a very careful 

 observer, assures me that of the two insects, house-flies and 

 Croton-bugs, his lizards certainly preferred the latter, but were 

 not particularly expert in capturing them. And now, assuming 

 that the eye-sight of these little reptiles is not highly developed, 

 what of the curious " pineal eye " which they possess ? Prof. 

 Macloskie has recently announced in " Science " that it " is so well 

 developed . . . that it may probably seem to warn its owner of 

 the advent of daylight. It is a lenticular, glassy area of the skin 

 of the vertex (about a millimetre in sagittal diameter), surrounded 

 by a yellow border, and having a dark spot in its center. The 

 dark spot is opaque, caused by a mass of pigment internal to the 



