NO. 3 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 



209 



systems, between which are some areas of short lamellae. The lacunas are oval ; 

 senile changes are frequent. The internal circumferential lamellae are frag- 

 mentary. 



Type III, C, senile. 



* RIGHT FEMUR OF A WHITE MALE. NO. 280, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 30 mm. ; lateral, 24.5 mm. 

 Antero-posterior diameter of medullary canal, 15 mm. ; lateral, 11 mm. 

 Medullary index, 29%. 



Structure. — The external circumferential lamellae form a narrow ring 

 around the bone. The section is mostly composed of well developed Haversian 

 systems with little inter-Haversian bone substance. 



The internal circumferential lamellae surround the medullary canal. 



Type III, C. 



* LEFT FEMUR OF A WHITE MALE. NO. 281, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 31 mm. ; lateral, 27 mm. 

 Antero-posterior diameter of medullary canal, 13 mm.; lateral, 10 mm. 

 Medullary index, 19%. 



Structure. — The external circumferential lamellae are fragmentary. The 

 section is composed of large, small, and irregularly shaped Haversian systems, 

 some of which show senile changes. 



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

 lary canal. 



Type III, C, senile. 



* RIGHT FEMUR OF A WHITE MALE. NO. 282, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 30 mm. ; lateral, 31.5 mm. 

 Antero-posterior diameter of medullary canal, 16 mm.; lateral, 13.5 mm. 

 Medullary index, 30%. 



Structure. — The external circumferential lamellae are fragmentary. The 

 section is composed of well developed, closely arranged Haversian systems. 

 As a rule, they are clearly distinct, but some of them are senile and obscure. 



The internal circumferential lamellae are fragmentary. 



Type III, C, senile. 



