The Green-frog, Rana clamata Daudin. 



71 



THE VOICE. 



About a month after the first appearance, the green-frog just begins 

 its croaking. Usually the males take their stand at the shallow edges 

 of the ponds and pools, though we have seen them in mid-pond on the 

 matted vegetation. The note is a low-pitched, short croak, with more 

 carrying power than that of Rana sylvatica or palustris. Its character 

 is as distinctive as that of the bullfrog, the other Rana which is in 

 voice at the same time. It is, however, never so powerful or prolonged 

 as in its larger congener. 



Croaking begins by the second or third week in May, the average 

 being May 10, the earliest April 26. The earliest records are: 



The air-records are at least as important as those of the water. 

 None of the air-maxima for the day of the croaking descend below 58 

 degrees and they average 71 degrees. The day previous to the record, 

 they are all (one exception) above 58 degrees and average 66 degrees. 

 If the water- temperature enters into the matter at all, it is solely the 

 surface-records. The surface-temperatures range from 64 to 72 degrees 

 or higher when the species begins croaking in real earnest. About 

 the first of June the voice of R. clamata is heard more frequently than 

 that of any other Rana. It continues quite commonly until the middle 

 of July or later. Thereafter, until the middle of August, their croaks 

 become much scarcer. After August, they are seldom if ever heard. 



THE MATING. 



In the males of the green-frog a development of the thumbs and webs 

 occurs similar to that in the other species of Rana. The male has a 

 yellow throat and a larger tympanum than the female. If the sexes 

 differ in size, it is the male which is the smaller. Mating is more active 

 at night than by day. It does not begin before the latter part of May. 

 With captive individuals it has been noted as early as May 22. The 

 interval between first croaking and actual mating may be considerable. 

 In our night collecting, we not infrequently come to locate special 

 places where a male may be found croaking several nights in succession. 

 Egg-masses have subsequently been recorded in such spots so often 

 that it has been found a good plan to keep such localities in mind when 

 searching for eggs by day or night. About such masses the original 



