NO. 3 COMPARATIVE HISTOLOGY OF FEMUK FOOTE 173 



The internal circumferential lamella; enclose the medullary canal. It is a 

 fairly wide band in the hitcral walls. The lacunae of tlie section are generally 

 oval. 



Type I-II-III, la, C. 



* RIGHT FEMUR OF AN ADULT PACHACAMAC INDIAN. NO. 14, U. S. NAT. MUS. 



Syn. Tab. IX 



Antero-posterior diameter of bone, L14 mm. ; lateral, 21 mm. 



Antero-posterior diameter of meduUaiy canal, 14 mm.; lateral, 10 mm. 



Medullary index, 38%. 



Structure. — Slight evidences of the horseshoe band are present. The la- 

 mellae are most pronounced in the anterior wall where tliey form a fairly wide 

 band. In the lateral wall the lamelte are separated into lamina;, between which 

 are small Haversian systems of the (la) differentiation. 



The eenti'al ring is composed of Haversian systems. In the outer and inner 

 wall inter-Haversian lamella> are ])resent. The internal circumferential lamellae 

 enclose the medullary canal. In the outer wall they expand iiitt) a wide crescent, 

 which is broken into irregularly shaped fragments by interrupting Haversian 

 systems. The lacuna^ are long, narrow, and oval. 



Type I-II-III, la, C. 



* RIGHT FEMUR OF A PACHACAMAC INDIAN. NO. 13, U. S. NAT. MUS. 



Syn. Tab. IX 



Antero-posterior diameter of bone, 16 mm.; lateral, 15 mm. 



Antero-posterior diameter of medullary canal, 8 nnn. ; lateral, 7 mm. 



Medullary index, 30%. 



Structure. — The section is surrounded, with the exceptidii of tlie posterior 

 ridge, by a horseshoe band of lamina' in tiie outer aiui anterior wall and of 

 Haversian systems of the (la) differentiation in (he inner wall. The lamina" 

 are frequently jierforaled by snudl canals and in the anterior wall they sud- 

 denly widen and occupy tlie whole wall. As they approach the inner wall they 

 bend around the inner anterior angle and are then displaced by very crude 

 Haversian systems. 



The central ring is rednced to a crescent in the onter wall. It is composed 

 of crude Haversian systems nnd lanielhe. 



The posterior ridge is not distinguishable from the lateral wall and con- 

 sists of Haversian systems and short lainiiue having a direction parallel with 

 the external surface. 



