208 SMITHSONIAN CONTEIBUTIONS TO KNOWLEDGE VOL. 35 



Structure.- — The external cironmferential lamellie form a narrow ring 

 around the bone. 



The section is composed of Haversian systems, which, in the anterior wall, 

 are separated by the fragments of a lamellar horseshoe band described else- 

 where. Many systems are senile. 



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

 lary canal. 



Type III, C, senile. 



BIGHT FEMUR OF A WHITE MALE. NO. 277, CR. MED. COLL. 



Pl. 35, Fig. 439. Syn. Tab. XI 



Antero-posterior diameter of bone, 32 mm.; lateral, 28 mm. 



Antero-posterior diameter of medullary canal, 17 mm.; lateral, 11 mm. 



The medullary canal is full. Medullary index, 28%. 



Structure. — External circumferential lamellse, interrupted by many Ha- 

 versian systems, surround the section. The central ring, irregular in width, 

 is composed of Haversian systems, somewhat irregular in shape, but well de- 

 veloped. The internal circumferential lamellte, expanded into a wide semi- 

 circular area in the inner wall, surround the medullary canal. 



Type I-III, C. 



* EIGHT FEMUR OF A WHITE MALE. NO. 278, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 29 mm.; lateral, 34 mm. 



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



Medullary index, 35%. 



Structure.- — The external circumferential lamellas are fragmentary. The 

 section is composed almost entirely of large, small, and irregularly shaped Ha- 

 versian systems. 



The internal circumferential lamellaj form a narrow enclosing ring around 

 the medullary canal. 



Type III, C. 



* RIGHT FEMUR OF A WHITE MALE. NO. 279, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 30 mm. ; lateral, 27 mm. 

 Antero-posterior diameter of medullary canal, 16 mm.; lateral, 14 mm. 

 Medullary index, 38%. 



Structure. — The external circumferential lamellaB are fragTiientary. The 

 section is comjDOsed almost entirely of large, small, and irregular Haversian 



