The Pickerel-frog, Rana palustris LeConte. 65 



April 6 (1910) to May 18 (1907), or 6 weeks. In any single year, 

 however, the period is about 3 weeks. The length of the breeding 

 time was 21 days in 1906; 20 days in 1907; 19 days in 1910. The fol- 

 lowing summary of the 1907 spawning story for three ponds is repre- 

 sentative of a normal year: 8 bunches on April 29; 15 bunches on April 

 30; 12 bunches on May 1; 30 bunches on May 2; 3 bunches on May 3; 

 2 bunches on May 14; 1 bunch on May 18. 



We have noted more spoiled bunches of eggs in nature in R. palustris 

 than in any other species of Anura. Sometimes all the bunches of a 

 pond may be in such a condition. We have already alluded to the 

 tendency of captive females not to lay for some time after being mated, 

 and then a few eggs at a time for a week or more. Almost invariably 

 these delayed complements are infertile. Again, we have an instance 

 of a female's laying without an attendant male (April 28, 1906) . Unlike 

 some of our records of similar phenomena, she was not separated from 

 a mating male, but was unattended when captured. As a result we 

 may suspect that the spoiled condition may possibly be due partly 

 to unattended and partly to delayed laying. 



In conclusion, one may expect that the species will begin laying when 

 the air reaches 50 to 61 degrees, and most certainly when 65 to 69 

 degrees are recorded, provided the water is 51 to 64 degrees. 



THE EGG-LAYING PROCESS. 



We have watched none of our species more carefully, both in the 

 laboratory and afield, yet previous to 1911 we had not seen the complete 

 egg-laying process, in all the 50 or more pairs of R. palustris observed. 

 It does not last long; for example, May 3, 1907, one of our mated pairs 

 in the laboratory had not laid at 3 p. m., but between 3 and 3 h 20 m p. m. 

 a fresh bunch of eggs was deposited. One of the best places to hunt for 

 mated pairs is underneath egg-masses already laid or at the base of a 

 suitable stick. 



Some observations in 1907 will serve to show the nervousness of the 

 mated females. At least four pairs were observed perched on a twig 

 in what appeared to be an egg-laying position; after a time one pair 

 left and until their capture hid for 20 minutes underneath the twigs 

 upon which they formerly were ; the second pair remained for 20 min- 

 utes on a twig which already had 2 bunches of eggs. In both instances 

 the female merely rested on the twig, holding with neither her fore nor 

 hind limbs. A third pair was discovered at Il h 40 m a. m. (May 3, 1907) 

 the female sitting astride a horizontal stem. She was semi-erect, her 

 fore limbs on a level with the stem; her hind limbs were not locked and 

 her feet did not hold the stem. At Il h 45 m , she brought both heels up 

 so that they touched under the twig; then she dropped one leg and 

 remained with one heel touching the stem; at 12 h 05 m her hind limbs 

 were both brought up and her feet came in touch with each other; at 



