24 



General Account of the Ithacan Anura. 



THE TRANSFORMATION. 



Transformation may begin in early June, but it occurs principally 

 from the latter part of June to the first or middle of August, especially 

 in July. Thereafter, until October or November, stragglers may trans- 

 form. The approximate order of transformation is given in the follow- 

 ing condensed table of data: 



From the above, one might derive the following groups based on the 

 period of transformation: The toad, the wood-frog, and the green-frog; 

 the peeper and the meadow-frog; the bullfrog; the pickerel-frog and the 

 tree-toad. The first three may vary in their order. Any one of them 

 might be a possible first to transform. In the same way, the peeper and 

 meadow-frog may change positions and occasionally the peeper tadpoles 

 anticipate those of the green-frog. In such a case, however, neither is 

 first or second in order of transformation. All our records of the bullfrog 

 place it securely in the sixth position. The pickerel-frog and the tree-toad 

 are very close in their order and interchange positions frequently. 



If a composite curve were made of the eight curves of transformation- 

 sizes, we would have a continuous record for seven forms from 7 to 

 to 38 mm. A gap of 5 mm. separates the end of this composite curve 

 from the beginning of that of the bullfrog, which transforms at sizes 

 from 43 to 59 mm. An examination of the curve for the seven forms 

 reveals three distinct modes and a suggestion of a fourth. These 

 modes come at 10, 18, 22, and about 31 mm., respectively, and show 

 clearly the groups of our Anura based upon transformation-size. They 

 are: The toad and the peeper (ranges, 7 to 12 mm. and 9 to 14 mm., 

 respectively; averages, 9.6 and 11 mm.; modes, 10 and 11 mm.). The 

 tree-toad and wood-frog (ranges 14 to 20 mm. and 12 to 21 mm.; aver- 

 ages, 16 and 16 mm. ; modes, 16 and 18 mm.) . The pickerel-frog and the 

 meadow-frog (ranges, 19 to 27 mm. and 18 to 30 mm.; averages, 24 and 

 24 mm. ; modes, 22 and 22 mm.) . The green-frog (range, 28 to 38 mm. ; 

 average, 33 mm.; mode, 31 mm.). The bullfrog (range, 43 to 59 mm.; 

 average, 53 mm.; mode, 54 mm.). (Plate ix, Fig. 2; Plate x). 



