60 The Leopard-frog or Meadow-frog, Rana pipiens (Schrcber). 



rainy, and the mortality consequently low, a region may have almost 

 a plague of small meadow-frogs. 



The size at transformation of 175 specimens varies from 18 to 31 

 mm., the usual range being 21 to 30 mm.; the average is 24 mm.; the 

 mode 23 mm. (Plate x, Fig. 6.) 



THE AUTUMNAL DISAPPEARANCE. 



About the middle of autumn the meadow-frogs begin to take to their 

 places of hibernation, usually in the first of October, when the light frosts 

 come. In the middle of October, with the approach of heavy frosts, they 

 are rarely seen. The greater part of our late records extend from 

 October 3 to November 26, the latest being: November 18, 1899; 

 October 31, 1902; November 5, 1907; November 26, 1908. So, when 

 November 1 comes, we may expect most of the meadow-frogs to be 

 under cover. An average of the very latest records gives November 12. 

 A consideration of all the late appearances (1899-1912) which we 

 have, gives maximum air-temperatures from 48 to 77 degrees, or an 

 average of 66 degrees for the day of the record, and gives minima from 

 34 to 61 degrees, or an average of 45 degrees; for the day previous, 

 maxima from 49 to 83 degrees, or an average of 64 degrees, and minima 

 with an average of 41 degrees. Apparently then, after they have first 

 entered their hibernation-quarters, they may emerge when the air of 

 late October or early November reaches 61 to 64 degrees. They enter 

 the mud of our marshes in great numbers and in such places the frog- 

 catchers secure them in abundance in early spring, rarely in winter. 

 In small ponds they seek the mud in the same fashion, but not in great 

 hordes. They spend the winter under stones in our ravines and rocky 

 streams, or beneath the flat stones on the riffles of our lowland streams, 

 in the same situations where the young of basses and other fish may be 

 taken, or beneath old logs under water. Whenever they seek very cold 

 streams or springs which remain open all winter, they are occasionally 

 recorded in the dead of winter, but are always more or less torpid. 



