The Pacific Tree Frog 



regilla ranges from sea-level to 10,000 feet in the vicinity of Mount 

 Whitney. Thus it occurs from the Lower Sonoran well up into 

 the Boreal Zone, equal to the difference in latitude between Florida 

 and Labrador, and the extension of its range is thus second to that 

 of no other Hyla in North America." 1 



If we capture several specimens of Hyla regilla, we are almost 

 immediately impressed by three facts: first, their great alertness 

 and activity; second, their great variation in colour and colour 

 pattern; and third, their rapid and marked colour changes. 



They are not quite as active and impossible to manage as 

 Hyla squirella of the Southern States; they compare more favour- 

 ably in activity with Hyla pickeringii of eastern North America. 

 These frogs are small, with bodies relatively slender and legs 

 unusually long, so we are not surprised at the number of the leaps 

 made and the distance covered with each movement. They 

 show little tendency to climb, and will remain at the bottom of an 

 uncovered moss-garden for days at a time without any attempt at 

 escape. 



Their variation in colour is great. They may be any shade 

 of grey, green, or brown, and sometimes are more or less vividly 

 marked with red. It is not to be wondered at that one not famil- 

 iar with the fact that colour is seldom a specific characteristic 

 should think that the lot contained several kinds of frogs. Most 

 of the frogs present only one colour or shade, but there are likely 

 to be several in a given lot that will combine two shades or two 

 colours. The back may be brown while the sides are green, the 

 head and shoulders may be red while the body posteriorly is 

 green, and so on. (See Colour Plate VIII.) 



Not only does the background of colour vary thus greatly, but 

 the colour pattern is so variable that at first sight it may be difficult 

 to see what are the elements of the common pattern. This com- 

 mon pattern consists of a triangular patch between the eyes and 

 lengthwise bands on the back. There may be small spots placed 

 irregularly between the bands, and on the sides of the frog below 

 the bands. But there is what seems to be nearly every pos- 

 sible disguise of the pattern. The triangle between the eyes 



1 F. C. Test. " A Contribution to the Knowledge of the Variations of the Tree^Frog Hyla Re- 

 gilla." Proc. U. S. Nat. Museum, vol. XXI, pp. 477-492. 



135 



