BONES 



49 



affect total length of the forelimb. The slightly delayed fusion 

 of both proximal and distal ends of the fibula, as compared 

 with the tibia, may explain the decided bowing of the fibula 

 from the tibia. 



Skull measurements. For data on the growth of the entire 

 skeleton see Chapter 6. 



TABLE ISA 



(A. B. Dawson, MS. '&). Age and sequence of fusion of the epiphyses in the 



long bones 



Humerus, distal epiphysis (capitulum and 

 Trochlea) 



Radius, proximal epiphysis.. . 



Tibia, distal epiphysis 



Fibula, distal epiphysis 



Ulna, proximal epiphysis 



Femur, head 



Femur, distal epiphysis 



Tibia, proximal epiphysis 



Fibula, proximal epiphysis 



Humerus, proximal epiphysis. 



Radius, distal epiphysis 



Ulna, distal epiphysis 



Cartilage interrupted at end of first 

 month. Fused during second 

 month 



Fused during third month 

 Fused during third month 

 Fused during fourth month 

 Fused between 25-31 months 

 Fused at 31 months 

 Cartilage interrupted 37 months 

 Cartilage interrupted 37 months 

 Cartilage interrupted 37 months 

 Cartilage interrupted 37 months 

 Cartilage complete 37 months 

 Cartilage complete 37 months 



Skull measurements have been made by Hatai ('07 c). 

 following description is extracted from his paper. 



The 



For this study 53 male and 51 female skulls of mature Albinos (rats 

 more than 150 days old) were measured. These skulls had been care- 

 fully cleaned and dried at room temperature. The following measure- 

 ments were made with vernier calipers: 1) the length of the entire 

 skull; 2) the fronto-occipital length; 3) the zygomatic width; 4) the 

 length of the nasal bone; 5) the height of the skull; 6) the width of 

 the cranium or the squamosal distance. In every case the maximum 

 length alone was recorded in millimeters. 



The horizontal straight line joining the tip of the nasal bone to the 

 end of the occipital bone is called the length of the entire skull. This 

 however is not exactly equal to the sum of the length of the nasal bone 

 and that of the fronto-occipital. 



The fronto-occipital length was determined in the following way: 

 Since the length measured with the calipers from the tip of the nasal 



