2 HENRY H. DONALDSON 



Physiological Laboratory of University College at Liverpool, 

 where I had examined R. temporaria in the same year. 



To both these gentlemen I desire to express my obligations for 

 their courtesy and aid. 



The results of these latest observations support completely 

 the conclusions based on the records of 1904. 



In the present communication therefore it is not necessary to 

 repeat the entire argument of the earlier paper, but merely to 

 present the evidence for the similarity of the earlier and later 

 records. 



For this purpose it will be desirable to print in full only the 

 original measurements for both years, while the important ratios 

 can be given in condensed tables accompanied by a few charts. 



The following are the tables of the principal measurements as 

 made on the three species in 1904 and 1909 



TABLE 1 

 Data on R. pipiens, Chicago 1904- 12 specimens 



