The Pickerel-frog, Rana palustris LeConte. 63 



may send them into the mud, but the sexual impulse is so strong that 

 within a very short time they come from their slight cover and resume 

 mating. The mating-places are often but not always in shallows. 

 Along the shores, within a short stretch, I have counted 20 or more frogs, 

 actively mating, to say nothing of those in the water. In one instance, 

 in a space 3 feet square, were 21 unmated males, 5 mated pairs, and 

 8 fresh egg-masses (representing 16 more frogs). In this species, when 

 mating is at its crest, we have observed mated pairs on the banks, a 

 phenomenon rarely if ever recorded for the others of the genus Rana. 

 We have found them on sandy shores in the hot sun, in shady stony 

 places, or in grassy edges of breeding-places — all, however, near a mating 

 area; and no doubt they were mated in the water, and not on land as 

 they approached the breeding-grounds. 



Usually, with most of the Anuran species, mated pairs captured in 

 the field generally laid the night of the same day of their capture, but 

 the rule did not always hold true with R. palustris; in fact, it seemed 

 the exception. To find pairs mated in the laboratory waiting two or 

 three days before ovulation was not surprising, but frequently pairs 

 from the field waited from 2 to 5 days before laying. In two instances, 

 in different years (one in an early season, the other in a late season), 

 each laid after remaining in the embrace a week. In 1912 a pair con- 

 tinued in the embrace 2 weeks before ovulation. 



The embrace is pectoral (Plate ii. Fig. 3) , the usual Raiia type. Often 

 it is maintained after the eggs are laid. Particularly is this true of pairs 

 mated in laboratory. On May 2, 1907, such a pair laid, but the male 

 continued his hold; this I broke, but he resumed a few minutes later and 

 so remained a week. Another pair brought from the field waited a week 

 before the female began to lay and she occupied several days in laying her 

 complement; thereafter they remained in the embrace 2 days. Similar 

 periods from 2 to 5 days have been observed with several other pairs. 



A few cross-embraces were noticed. On April 7, 1908, a male Rana 

 palustris grasped a female Rana clamata ; on the following day it was found 

 that he had the right hand dug into the axil, Bufo fashion, while the left 

 arm and hand reached around to the middle of the breast, Rana mode. 

 Once he lost his hold and regained a lumbar amplexation. This he kept 

 only a short time, working slowly up to the axillary embrace. Several 

 times males have mated with females of R. pipiens,Sind once a male em- 

 braced a Bufo lentiginosus americanus. Similarly males of the above 

 three species have been recorded mating with females of R. palustris. 



One peculiar amplexation of R. palustris was noted. On April 23, 

 1908, a vigorous male was placed with a pair which had laid, but had 

 continued in the embrace. The extra male seized the spent female 

 while still clasped by her former mate; he apposed his venter to hers and 

 held her back of her arms. We have no records of abnormal embraces 

 with other than Anuran forms, as no opportunity was afforded for it. 



