ANTHROPOMETRY 123 



terized by the presence of a distinct additional surface on the shaft. 

 The formation of the surface differs in the various bones. In the 

 tibia the additional surface results from a division into two, by a 

 vertical ridge, of the posterior surface; in the femur it is the anterior, 

 in the radius the external, and in the ulna the posterior surface, which 

 occasionally, through the influence of a vertical ridge, shows a forma- 

 tion of a distinct additional plane; in the humerus, finally, a new, 

 anterior surface results occasionally by the broadening out of the 

 anterior border of the bone. The cross section of the shaft in these 

 cases differs from lozenge shape (more or less) to a more even quad- 

 rangle. 



A special class of modifications of the form of the shaft is that 

 where one or more surfaces of the bone show a pronounced concavity. 

 We find such types (3, 3a, 3b,) particularly in the fibula, but also in 

 the tibia, ulna and radius. In the fibula the concavity affects es- 

 pecially the external, but also the internal, and occasionally both the 

 external and internal, and even the posterior surfaces; in tibia the 

 character is observed on the external, and in the ulna and radius 

 mainly on the anterior, flexor, surface. 



Types 5, 6, e and r, are widely differing forms of the shaft of some 

 of the long bones; all these types have, nevertheless, two features in 

 common, and that is an indistinctness or complete absence of one or 

 more of the borders of the bone, with marked convexity of two or all 

 the surfaces. 



Type 5 occurs occasionally in the tibia and frequently in the radius. 

 It is marked by the convexity of the posterior tibial and external 

 radial surface, and by indistinctness of the internal and sometimes also 

 the external border in the tibia and the anterior and posterior borders 

 in the radius. In both bones, but particularly in the tibia, this type 

 of form represents a deficiency in the differentiation of the bone. 



Type No. 6 occurs in the tibia, femur and humerus. The shaft is 

 plano-convex. Types e (elliptical) and r (round, cylindrical) are found 

 in the femur. 



The condition of flatness in long bones occurs quite independently 

 of the shape otherwise of these shafts. Flatness is not only found in 

 the tibia, but also in the fibula (lateral), in the femur (antero-posterior 

 of whole shaft, and, independently, antero-posterior of the upper 

 part of the shaft, below the minor trochanter), and in the humerus 

 (lateral). The flat femur (whole shaft) occurs almost exclusively in 

 whites and independently of the flatness of other long bones. It is a 



