38 The Peeper, Hyla pickeringii (Holbrook). 



continuall}^ at the surface, and consequently are much darker in colora- 

 tion than the less active females, which keep more to cover. At night 

 both are much lighter and pop into view at once when light is flashed 

 on them. The same result is frequently noted when mated pairs are 

 captured at day. "Whenever they arise to the surface the male only 

 is exposed. He may be as dark as the darkest dead leaves in the pond, 

 the female beneath being much lighter. 



In the customary weather of spring, mating generally begins about 

 April 1 and continues until Maj^ 1 or later. In one instance as late as 

 June 4 (1902), at one of our best collecting-spots, Mr. T. L. Hankinson 

 reported "two specimens were found clasped and hopping about the 

 muddy grass-sheltered ground near a pond." The earliest record of 

 mated pairs is March 30, 1907. Mating takes place largely at night, 

 though in some cases pairs have been captured in forenoon, afternoon, 

 or at midday. The embrace is axillary (Plate xiii. Fig. 4), and the 

 smaller male holds the female behind and slightl}^ above or on the plane 

 of the shoulder, the hands with fingers folded back being in the axils 

 of the female about half an inch back of the insertion of the arm. The 

 gular sac in this species, as in the tree-toad (Hyla versicolor), seems to 

 have also the secondary function of helping the male keep his hold 

 of the female. In this species the sexual ardor is no less strong than in 

 forms much larger. Often mated pairs when captured would break 

 their holds, but if immediately put together they resumed their em- 

 braces before my return to the laboratory. All of the mated pairs 

 captured afield laj^ by the following day, suggesting that they probably 

 do not remain in the embrace for several days preceding ovulation. 



A vigorous male which was accidentally placed in the Rana sylvatica 

 jar embraced a male of this species March 31, 1907. When several 

 males were placed with Chorophilus triseriatus, cross-embraces by males 

 of both species ensued. On March 30, 1907, several eager males were 

 placed in the common Amphibian jar and within a short time they began 

 to embrace an Ambystoma. As many as three have been recorded 

 clasping the head alone; and the same three presented a ludicrous sight 

 arranged along the back of this salamander, which in this case was 

 not disturbed, as in the case of the embrace of the male Rana sylvatica. 



A few peculiar embraces within this species were noted. Once 

 a female was in the possession of two males, the second above the first, 

 and with a hold just ahead of the arms of the female. Sometimes 

 a male will seize another male and have its fore limbs dug into the groin 

 just ahead of the hind limbs of the male seized, with the face caudad. 



OVULATION. 



In the laboratory ovulation has usuall}^ begun at night, sometimes 



extending into the following day. In the field all our observations on 



spawning were made by day. Invariably we chanced upon them when it 



was already begun, never at the initiation of egg-laying. We believe 



