The Tree-toad, Hyla versicolor LeConte. 



47 



the chorus, I collected every evening for a week from 9 to 11 p. m., 

 and each excursion yielded 6 or more males (and as many more were 

 seen), but not a female. Furthermore, from careful searching in that 

 time, no signs of eggs were found. The first eggs were taken 1^ weeks 

 after the beginning of the chorus. In 1907 the males arrived two days 

 previous to the females. 



The duration of individual mating is not very long. In all the mated 

 pairs captured, we recorded eggs the night of their capture, whether the 

 males were left in the embrace with the females or removed. Mating 

 is most active at night. By day, the tree-toad is less active, sometimes 

 remaining in the water, or perching a few inches or feet above the water 

 on grass, sedges, or ranker vegetation, ordinarily in green livery. 



We have records of males mating with partly or fully spent females, 

 with which they have or have not formerly mated. In captivity 

 males will seize other males, but not retain them beyond a few minutes 

 or hours at the most. 



OVULATION. 



The period of ovulation may last a month or more. Generally 

 20 to 35 days intervene between first appearance and first eggs, and 10 

 to 15 days between first arrival of species at a pond and first eggs. 

 Ovulation normally begins the very last of May, reaching its crest in 

 June. An average of all first dates gives May 25; or with the elimina- 

 tion of one very early date, June 2 ; and an average of crests comes June 7. 

 The range of first breeding records extends from May 10 to June 17. 

 The first egg-records and the crest-records are as follows : 



In all instances the maximum air-temperatures for the day previous 

 were from 72 to 83 degrees, averaging 77 degrees; for the day of the 

 record, 61 to 89 degrees, averaging 77 degrees. 



The crests follow soon after the initiation of ovulation. They come 

 at maxima ranging from 73 to 84 degrees for the day previous, or with 

 an average of 79 degrees; for the day of the record from 74 to 87 

 degrees, or with an average of 79 degrees. Then, from 61 to 87 degrees 

 seems the range, with 72 to 79 degrees the common effective temperature. 



The egg-laying may extend into July. In 1906 the last record for 

 eggs was July 3; in 1907 it was June 21. 



