Variation in Hooks of Dog-Tapeworms 27 



2. As the hook increases in length, its strength increases rela- 

 tively faster than the length of its claw. 



3. The length is uniformly the least variable part of the hook, 

 while the curvature of the hook is on the whole the most variable. 



4. The specimens of both T. serrata and T. serialis found here 

 have their small hooks approximately of the size found else- 

 where, while in the dimensions of the large hooks they excel 

 greatly. 



5. The percentage of the total variability exhibited by the in- 

 dividual is nearly constant, and amounts to a little over 50 per 

 cent. 



6. The correlation between the large and the small hooks on 

 the same head is .30i.11 for T. serrata, and .38+. 14 for T. 

 serialis. 



217 



