48 



The Tree-toad, Hyla versicolor LeConte. 



Inasmuch as this species lays at the surface of the water, the air- 

 temperatures probably are as influential as the water-temperatures of 

 the bottom or median plane of the water. The water-temperatures, 

 however, range from 67 to 75 degrees with an average of 71 degrees, a result 

 not much different from the effective air-temperatures already derived. 



The female tree-toad will lay without attendant males. In one case 

 a pair was allowed to remain in the embrace in water; another pair 

 was separated, but the female remained in water; and a third pair was 

 separated and the female left in a dry jar. All three females, two 

 unattended and one attended, laid their egg-complements over night. 

 In another case, a female which was brought into the laboratory began 

 laying without an attendant male, nor was she previously mated so far 

 as we know. After 200 eggs were deposited, a male was placed with 

 her. Later in the day, the mated pair completed the complement. 



THE EGG-LAYING PROCESS. 



For a long time the manner of deposition in this form was unknown. 

 Usually, in the field, the mated pairs were taken at the edge of the 

 ponds, the hind parts just touching the surface of the water or the lower 

 third or half of the body submerged. Another favorite attitude with 

 single individuals, when away from the edge of the pond, was to rest 

 the fore limbs on a Potamogeton leaf or similar floating surface, keeping- 

 just the dorsum of the head out of the water. It was known that a 

 female in laboratory might lay as many as a thousand or more eggs, 

 yet in nature we always found them floating on the surface in groups 

 of 4 to 25, either attached or free. This meant either that the pair 

 laid them in packets or else that soon after laying these packets floated 

 away from one original mass. The second alternative is no longer 

 tenable from actual observations of a pair which was depositing at 

 8 h 30 m p. m., June 15, 1907: 



The table is to be read somewhat as follows: At the first sexual 

 period there were three distinct fertilizations and three emissions, a 

 fertilization and an emission being simultaneous. Between the first 

 fertilization and emission and the second one there was an interval of 



