The Pickerel-frog, Rana palustris LeConte. 69 



THE TRANSFORMATION. 



This may begin the last week in July, but by far the greater number 

 of larvse transform in August. In 1906 our first record was July 24; 

 in 1907, July 14 and 30; in 1908, July 25; in 1909, July 22; in 1910, 

 July 26; and in 1911, July 25. An average of the first records is July 

 23. In 1907 a large proportion of the larvae transformed the first week 

 in August, though the stragglers continued to transform until Septem- 

 ber 1. In 1912, stages from the mature tadpoles with small hind legs to 

 transformation were secured on September 1, and surely some of the 

 material could not have transformed before September 15 or October 1. 



The size at transformation of 61 specimens varies from 19 to 27 mm.; 

 the average is 24 mm., the mode 23 mm. (Plate x, Fig. 5.) 



THE AUTUMNAL DISAPPEARANCE. 



Our latest records for this species extend from October 6 to 24. The 

 maximum air-temperatures for the day previous to the record and for 

 the day of the record show averages of 71 and 72 degrees, respectively, 

 or temperatures from 63 to 83 degrees. When the frosty weather 

 begins they betake themselves to cover. Quite frequently, after such 

 periods, they can be found in our ravines under stones near the water's 

 edge or in the water. Occasionally they are more or less active the 

 whole 3^ear, provided they happen to be in a spring which remains open 

 throughout the winter. We had long suspected that this species 

 hibernated in the ravines more than any other Anuran at Ithaca. 

 To determine this question we placed a trap at the mouth of a ravine 

 to catch the Anura which might migrate to the swamp below for spring 

 breeding purposes. For a week we secured plenty of Ra7ia palustris, 

 and frequently more of them than of all the other species combined. 



