The Peeper, Hyla pickeringii (Holbrook). 



39 



that every year when the species reaches the chorus-stage, spawning 

 also begins or is already in progress. An examination of the following 

 egg-laying records shows no maximum air- temperature below 51 

 degrees, and none for day of record below 50 degrees, a condition closely 

 following the 54 and 52 degrees given for the chorus stage. On March 

 29, 1910, in the exact place at the bottom of the pond where ovulation 

 was in progress, a temperature of 59 degrees was secured; at the surface, 

 60 degrees. 



THE EGG-LAYING PROCESS. 



As the time for egg-laying draws near, the female becomes very rest- 

 less. No other Anuran of this region appears more nervous. If con- 

 ditions are not just to her liking, she leaves at once. The first pair 

 taken illustrated this very well. On April 25, 1904, we placed a pair 

 in a large aquarium If feet in diameter. It was If feet high, had a wire- 

 gauze screen over the top, and 2 inches of water in it. At 11 p. m., 

 when I left the laboratory, they were still in the jar, but the next morn- 

 ing they were gone. The female with male attached, no doubt, had 

 climbed the smooth perpendicular surface of If feet, lifted the un- 

 weighted screen, and sought other quarters. 



In the evening of April 28, 1907, three pairs were captured. At 

 8 h 30 m a. m., April 29, all three were ovulating. In every pair the fertili- 

 zation took place when the pair was in a semi-horizontal or oblique 

 position. At the moment of fertilization the male drew its vent down 

 to meet the slightly upturned vent of the female. Immediately the 

 female assumed an erect position, her hind limbs drawn up behind. 

 The vent was then extended horizontally forward and the emission of a 

 single egg followed. 



The female, when egg-laying, hugs the stem or stick with the fore- 

 arms. Both hind limbs are drawn up, so that the heels touch each 

 other or one is a little cephalad or caudad of the other. None of the 

 females just mentioned was seen lying lengthwise of a stem. Gener- 

 ally, a female came up from the side and faced at right angles to it. 

 This position she kept for one or two, rarely four emissions. Usually 

 she changed position after each emission, though it might only be to 

 take the other side of the stem. Sometimes, when laying on the bottom 



