114 Vniversitij of Calif or nia PuhVwations in Zoology [Vol. 11 



value as specific constants is impaired, owing to the effect of 

 variation in length of individual upon the number of teeth pos- 

 sessed. In other words, if the number of teeth increase or 

 decrease as the aniiiuil increases in length, it is evident that the 



50 



40 — 



30- 



20- 



10- 



3 4 5 6 7 



Fiif. 1 



nature of the histogram will vary according to the number of 

 specimens of any particular length constituting the popuhitimi 

 con.sidered. It is necessary, therefore, to ascertain the relation 

 between number of teeth and length of specimen. 



