NO. 3 COMPARATIVE HISTOLOGY OF FEMUR FOOTE 191 



The internal circumferential l-amellse form a narrow ring around the medullary 

 canal. 



Type III, C, senile. 



EIGHT FEMUR OF A WHITE MALE. NO. 167, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 30, Fig. 392. Syn. Tab. X 



Antero-posterior diameter of bone, 27 mm. ; lateral, 25 mm. 



Antero-posterior diameter of medullary canal, 14 mm. ; lateral, 11 mm. 



The medullary canal is full. Medullary index, 30%. 



Structure. — The external circumferential lamellfe are fragmentary. For 

 the most part, Haversian systems form the external boundary of the section. 

 The central ring is composed of Haversian systems and inter-Haversian lameUse 

 in the inner wall and of Haversian systems elsewhere. The internal circum- 

 ferential lamellae are fragmentary. 



Type III, C, senile. 



RIGHT FEMUR OF A WHITE MALE. NO. 172, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 30, Fig. 393. Syn. Tab. X 



Antero-posterior diameter of bone, 32 mm.; lateral, 31.5 mm. 



Antero-posterior diameter of medullary canal, 17.5 mm.; lateral, 18 mm. 



The medullary canal is full. Medullary index, 45%. 



Structure. — A narrow band of external circumferential lamellae, somewhat 

 fragmentary, forms the external boundary of the section. The central ring is 

 composed of Haversian systems, well developed and of varying sizes. In the 

 anterior and inner wall, the systems are separated by a little inter-Haversian 

 structure. Many senile systems appear. Few cross canals are seen. The 

 internal circumferential lamellfe are fragmentary. 



Type III, C, senile. 



BIGHT FEMUR OF A WHITE MALE. NO. 242, CR. MED. COLL. 



Pl. 31, Fig. 394. Syn. Tab. X 



Antero-posterior diameter of bone, 32 mm.; lateral, 27 mm. 



Antero-posterior diameter of medullary canal, 1!) inni.; lateral, 15 mm. 



The medullary canal is full. Medullary index, 49%. 



Structure.— The external circumferential lamellae are fragmentary. "Re- 

 mains of the lamellar liorseshoe are found in the inner wall. 



The central ring forms nearly the whole of the section and is composed ol' 

 Haversian systems, many of whicli show senile changes. 



The internal circumferential lamellas form a naridw ring aronnd the incdnl- 

 lary canal. 



Type III, C, senile. 



