206 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 35 



Structure. — The external circumferential lamellae are fragmentary. The 

 section is composed, for the most part, of well developed Haversian systems 

 with very little inter-Haversian bone substance. Many of the systems are 

 senile. The cross canals are fairly numerous. 



The internal circumferential lamellae form a very narrow ring around the 

 medullary canal. 



Type III, C, senile. 



* RIGHT FEMUR OF A WHITE MALE. NO. 271, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 31 mm.; lateral, 32 mm. 



Antero-posterior diameter of medullary canal, 17 mm. ; lateral, 15 mm. 



Medullary index, 35%. 



Structure. — The external circumferential lamellae form a narrow ring 

 around the bone. 



The section is composed almost entirely of large, small, and irregularly 

 shaped Haversian systems. Their lacunae are generally oval. The cross canals 

 are not numerous. Senile changes are few. 



The internal circumferential lamellae form a narrow ring around the medul- 

 lary canal. 



Type III, C. 



* EIGHT FEMUR OF A WHITE MALE. NO. 272, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 33 mm. ; lateral, 28 mm. 



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



Medullary index, 26%. 



Structure. — The external circumferential lamellsE appear as rather wide 

 bands on both sides of the posterior ridge. These bands are interrupted by 

 small Haversian systems and become narrower as they approach the anterior 

 wall where they are fragmentary. The remainder of the section is composed 

 of Haversian systems with oval and long lacunae. 



The internal circumferential lamelte form a narrow ring around the medul- 

 lary canal. 



Type III, C. 



* RIGHT FEMUR OF A WHITE MALE. NO. 273, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 28 mm. ; lateral, 29 mm. 

 Antero-posterior diameter of medullary canal, 15 mm.; lateral, 12 mm. 

 Medullary index, 29%. 



