Donaldson, Ainerican and European Frogs. 



127 



research of Donaldson and Schoemaker ('00). These cases 

 are averaged in groups of five. 



Twelve (12) specimens of R. pipiens, these being the same as 

 are given in Table 7 and averaged in groups of four (observations 

 by Dr. Hatai). Both of the foregoing series of measurements 

 v^ere made on the fresh specimens. 



Ten specimens of R. pipiens, after fixation in formalin, aver- 

 aged in groups of five, and ranging in total length from 128-174 

 mm. This was the series used to control the measurements on 

 the European frogs received from Zurich in 1898. 



From the Zurich series of 1898, there were taken one group of 

 five esculenta, ranging in total length, after fixation, from 128-170 

 mm., and also a series of fifteen R. temporaria, averaged in groups 

 of five, and ranging in total length, after fixation, from 151 to 179 

 mm. 



It seems fairest to tabulate the fresh, separately from the fixed 

 material, so the first lot, entirely R. pipiens, is given in Table 5. 



table 5. 



R. pipiens. Percentage values of length of the entire central nervous system, the 

 total length of the frog being taken as the standard. Measurements on fresh 

 specimens. 



Averages of 



TABLE 6. 



Showing the same relation as Table 5. All measurements on material fixed in 



formalin. 



Species. 



Per Cent Value of 

 THE Length of the 

 Entire Central 

 Nervous System. 



R. pipiens . . . . 

 R. esculenta. . . 

 R. temporaria: 

 R. temporaria. 

 R. pipiens . . . . 

 R. temporaria. 



17.9 

 16.9 

 16. z 

 16.4 

 16.0 



