126 Journal of Comparative Neurology. 



the length of the entire frog, and thus determine what percent- 

 age of this length is represented by the leg bones. 

 TABLE X. 



Percentage of the length of the entire 

 frog represented by the sum of the 

 Group, lengths of the leg bones. 



iJ:} 68.7/. 



III. 68. 79^^ 



IV. 66.8/, 



In this case again the absolute numbers for virescens do 

 not agree with those for catesbiana — the former ranging about 

 2'fo higher. In both species, Groups I and II give the highest, 

 and Group IV the lowest percentage, and although slight, the 

 differences between the groups are probably significant. 



To determine whether the proportions for the lengths of 

 the leg bones are constant in the several groups, the sum of the 

 lengths of the femur, tibia and foot can be taken as represent- 

 ing 100% of the length of the leg bones, and then the percent- 

 age value of the separate bones can be calculated on the basis 

 of their respective lengths. 



Treating in this manner the records comprising the several 



groups we obtain the proportional lengths set forth below. 



TABLE XI. 



Proportional lengths of 

 Group. Femur Tibia Foot 



The percentages for the several groups do not show any 

 variation which can be considered significant. 



These numbers indicate that in virescens as compared with 

 catesbiana, the tibia is proportionately long, the femur and foot 

 short, but even here the differences are small. 



Summarizing the differences thus brought out between 

 the two species, they are found to be as follows : 



As compared with catesbiana, virescens has proportionally 

 heavier hind legs, though the muscles of the thigh are lighter 



