46 The Tree-toad, Hyla versicolor LeConte. 



The first tree-toads of any region may be heard in trees around their 

 breeding-places for several days before they are recorded in the ponds; 

 e. g., June 3, 1907, males were recorded in trees about the college pond; 

 but it was not until June 9 that they entered it. About a pond near 

 the athletic field they were heard two days (June 8 to 10) before they 

 reached the pond. In 1906 an interval of 4 days was recorded for the 

 college pond (May 13 to May 17). 



When the tree-toads are in chorus, their abundance is amazing, and 

 the chorus is at times deafening when near at hand. In and about the 

 ponds they may be taken in considerable numbers, e. g., in one case, 20 in 

 15 minutes; in another, 9 in 20 minutes. In the grass and other areas 

 about the ponds, one may find them migrating to the pond. At the 

 breeding season, about the edges of the ponds and in the overhanging 

 bushes, the collecting proves best. In the ponds, logs and flat vegetative 

 surfaces prove the most likely perches. An experiment was tried on one 

 croaking male perched with three others on a log. To show how tame 

 he was, and at the same time to see how dazed he would be by a strong 

 light, I stroked him with the lighted end of my flash-light. This was 

 done 91 times without his stirring. He croaked just the same. When 

 he stirred, it was only to change position to another place on the log, 2 

 inches away. The operation could readily have been repeated. Then, 

 too, when captured between trills, the tree-toads sometimes have the 

 sacs half-inflated, which in collapsing, produce a squeak, as in Hyla pick- 

 eringii. At times tree-toad males seem quite individualistic in their 

 calls, and an individual tree-toad may give one or two voice-forms 

 totally unlike the normal and better-known call. 



In some ponds the species may be heard for a month or more after 

 their first arrival ; at the college pond we have the following records : 



First arrival: May 17, 1906; June 9, 1907; June 5, 1911. 



Last heard at pond: June 22, 1906; July 15, 1907; July 6, 1911. 



Some, however, leave the breeding-places by the middle of June. In 

 midsummer they resort to the trees again, and during the latter part 

 of August and through most of September the males may be heard from 

 time to time. 



THE MATING. 



The males are very fond of places full of lily-pads, Potamogeton 

 leaves, algae, or other large floating surfaces, suitable as resting-places 

 or perches. In small ponds it is not uncommon, with one sweep of the 

 flash-light, to see as many as 8 or 10 males thus perched. 



The same kind of embrace obtains as in Hyla pickeringii (Plate iv, 

 Fig. 5). In the aquarium it is often noticed that the male uses his 

 viscid gular sac as a means of attachment, augmenting his discs. When 

 mating, this sac often is partially inflated and doubtless helps the male 

 to retain his hold. It is doubtful if the females repair to the breeding- 

 ponds at the same time as the males. In 1906, from the beginning of 



