Rana heckscheri 395 



The paragraph before was more in the nature of negative evidence and 

 conjecture but on June 8-10, 1928, countless mature tadpoles were approach- 

 ing transformation. Our series of 89 frogs transformed and transforming 

 could have been materially increased had we wished. Probably as in Rana 

 catesbeiana, R. damitans and some of the other large bodied tadpoles trans- 

 formation is largely accomplished by the end of June. A few of the trans- 

 formed ones (40-49 mm.) might indicate transformations in May, and some 

 of the mature, about-to-transform tadpoles might not transform before July 

 I or possibly July 15. In other words before the period in which we observed 

 them in 1922. 



Size. In 1922 we held that "some of the largest tadpoles with large bodies 

 and well developed hind legs had body lengths of 32-41.5 mm. and the trans- 

 formation size probably falls within this range." On June 8 and 9, 1928, we 

 took 89 transformed or transforming frogs: — transformed (41) or nearly so 

 with short tails (3-29 mm.) (48 specimens). Almost invariably if there was 

 an appreciable stub the mouth was not the full-developed frog mouth. We 

 can properly say that the range of size reaches from 31-49 mm. The 89 

 start with three at 30 mm., reaches the mode at 33 mm. with 22 specimens, 

 and almost ceases with three at 38 mm. The record onwards is i at 39 mm., 

 I at 41 mm., one at 43 mm., 44 mm. and 45 mm., 3 at 46 mm., i at 48 mm, 

 and I at 49 mm. We thus see there are only nine of the 89 which are 40 

 mm. or more. The normal range is from 30-39 mm. yet there is clearly 

 another smaller group with a mode about 46 mm. The average of the 30-39 

 mm. is 34 mm. or of the whole 89 specimens from 30-49 mm. is 35.5 mm, 



GROWTH 



On August 18 we captured at least four different sizes of frogs some (8-10 

 frogs). The same evening we later lost all but three of them. These are 56, 

 82 and 95 mm. respectively. The range of body length of seven large tadpoles 

 with hind legs well started is 36-40, average 38, mode 39 mm. It is true we 

 have given 32-40 or 41 for transformation size but the bulk of it probably 

 comes within the narrower range of 36-40. This would give us 32-41 for 

 transformation. The 56 mm. specimen may be two years old, the 82 mm. 

 specimen a four year old and the 95 mm. specimen a five year old. They were 

 all taken at the same time and there was another group of sizes between 

 56-82 mm. amongst the 8-10 specimens originally captured. (1922). 



The conclusions above of 1922 are hardly correct for the 56 mm. specimen 

 — the smallest frog we then had. If transformation sizes of June 8 and 9, 

 1928, vary from 30-49 mm. the 56 mm. can not be two year olds. It seems 

 quite likely that some of the frogs which are almost transformed may retain 

 their tails some time thereafter or that transformation may at times be 

 delayed beyond the normal 30-39 mm. The premise of 1922 that 32-41 mm. 

 was the probable transformation size is not far from the normal 30-39 of 

 1928. An unusual 49 mm. transformed frog would have to grow only 7 mm, 

 to attain 56 mm. which can hardly be a two year old. 



