The Tree-toad, Hyla versicolor LeConte. 51 



THE LARVAL PERIOD. 



This period extends 50 to 60 days after egg-deposition. In 1906 the 

 first eggs were laid May 27, and the first larvae were transformed 

 July 31, giving a total of 65 days for the egg and larval period. In 

 1907 the fii'st eggs were laid June 11 in one pond, and the first trans- 

 formed individuals from the same place were recorded July 31, a total 

 of 50 days. In 1908 the fu'st eggs were laid May 21 in the college pond; 

 on July 6, 46 days later, some approached transformation, while on 

 July 22 several were recorded in adult form (62 days from the egg 

 deposition). In another pond, ovulation was begun on May 22, and 

 on July 7, 46 days later, transformation was completed. In 1911 in 

 one place eggs were deposited Maj^ 10; by Jul}' 18 all the tree-toad 

 tadpoles were transformed (59 days later). 



THE TRANSFORMATION. 



This takes place largely during the last of July and the first of August. 

 For 1906 and 1907 it began July 31. In 1907 the period of transforma- 

 tion was nearly completed by August 15. In 1908 and 1909 the species 

 began this stage July 21 to 25. The first transformations were found 

 July 30, 1910, and July 18, 1911. The range appears to be from July 

 18 to August 15, with the average of the first transformations on July 25, 

 the mode on July 31. In the late autumn of 1911 the tadpoles were 

 still recorded in one pond in which the authorities had placed copper 

 sulphate to keep out the algse; this possibly retarded the transformation 

 of the tree-toad tadpoles so that they passed two or three months 

 beyond the normal transformation period. The transforming individ- 

 uals can best be secured along the edges of the pond or on floating lilies 

 and vegetation. At other times they may be taken in the vegetation 

 around the ponds or on the grass, sedges, and water plants at distances 

 of 2 or 3 feet above the level of the water's surface. The size at trans- 

 formation of 87 specimens varies from 13.6 to 20 mm. ; the average is 

 16 mm. ; the mode, 16 mm. (Plate x. Fig. 3.) 



THE AUTUMNAL DISAPPEARANCE, 



In midsurmner, or before, they betake themselves to the trees again 

 and by July 15 become infrequent. From this date to the latter part of 

 August they are usually silent, but may trill sometimes during the 

 sultry evenings of July, before or after a rain. Frequently they 

 remain until August 1, not far from the pond or breeding-spot to which 

 they repaired in early May. From August onward they often wander 

 to localities quite remote from the water. During the latter part of 

 August, through most of September, and rarely in the first days of 

 October, the males may be heard from time to time. Our latest autumn 

 records of tree toads are: October 24, 1905; September 18, 1907; and 

 October 9, 1909. 



