General Account of the Ithacan Anura. 5 



by March 19, and in very late seasons sometimes not until April 27 

 (two weeks beyond that of the first group). These two never emerge at 

 lower air-maxima than 48 or 53 to 58 degrees, and usually at average 

 air-maxima from 57 to 67 degrees. The pickerel-frog hibernates in the 

 water and usually appears when the water is at least 45 to 53 degrees. 



In early springs, the second and first groups occasionally appear at 

 the same time, e. g., in 1903, when the temperature reached 68 to 75 

 degrees, four of the first five appeared on the same day, March 19. 

 Furthermore, the interval between the dates of appearance for the 

 wood-frog (the last of the first group) and the toad (the first of the 

 second group) is only one da}*". In four of twelve years the toad has 

 appeared with the wood-frog or anticipated it by one day. In all these 

 mergings of first and second group appearances, the lowest air-maxima 

 never descended below 48 degrees, which is 7 degrees higher than the 

 lowest of the first group. 



The green-frog appears, on the average, about April 7, or four days 

 later than the last of the second group. In very early seasons, it has 

 emerged as early as March 28 (9 days later than the second group), 

 and in very late springs as late as April 20. The lowest air-maxima of 

 any of its appearances are from 54 to 61 degrees, and the average air- 

 maxima from 61 to 69 degrees. It hibernates beneath the water and 

 the effective water-temperatures begin at 46 to 58 degrees and upward. 

 Its appearance in three years has been synchronous with that of the 

 pickerel-frog, which may appear at air-maxima 6 degrees lower, or 

 at water-temperatures 1 degree lower. In these three years, the air- 

 maxima were from 58 to 72 degrees. In 1908, on March 28, when the 

 air-maxima suddenly ascended to 72 degrees, this species, the toad, 

 the pickerel-frog, and the wood-frog came out on the same day. 



The tree-toad appears on the average about April 28 (21 days after 

 the green-frog). In very early springs, it has appeared as early as 

 April 16 (19 days after the green-frog), and, in backward seasons, as 

 late as May 8 (18 days after that of the green-frog). The lowest air- 

 maxima of its appearance are from 58 to 61 degrees and the average 

 air-maxima of all appearances are 66 to 70 degrees. 



The bullfrog is the last to appear. It comes, on the average, about 

 May 20 (34 days after the tree-toad) ; its earliest appearance is May 11 

 (25 days after the tree-toad), and its latest appearance is June 4 (27 

 days after the tree-toad). The lowest air-maxima at appearance are 

 68 to 75 degrees; the average of all appearances is from 76 to 79 de- 

 grees. It is our most aquatic form and emerges when the water 

 reaches 57 to 69 degrees. 



In conclusion, we see that the average dates of appearance range 

 from March 26 to May 20. In the first 12 of these 55 days, six of 

 the eight species appear. The extreme range of first appearance extends 

 over 101 days, or from March 5 to June 4, a period almost twice the 



