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SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 35 



Structure. — Beginning on the outer side of the posterior ridge is a wide 

 band of lamella; in which are many Haversian systems. The band occupies 

 about one-half of the wall and is gradually displaced by Haversian systems in 

 the anterior wall. In the inner wall the continuation of the band is indicated 

 by concentric rows of elongated systems. Underneath the band is a central 

 ring of Haversian systems with senile changes. Many canals extend in all 

 directions in the two bands. The two bands taken together are the remains 

 of the horseshoe of lamella? so often present in the lower types of bone. The 

 posterior ridge is composed of small, irregularly shaped Haversian systems 

 with inter-Haversian lamellae. 



A narrow band of internal circumferential lamellae surrounds the medullary 

 canal. 



Type I-ILI, C, senile. 



LEFT FEMUR OF AN ADOLESCENT CHICAMA INDIAN. NO. 7, U. S. NAT. MUS. 



Pl. 27, Fig. 351. Syn. Tab. IX 



Antero-posterior diameter of bone, 18.5 mm.; lateral, 19 mm. 

 Antero-posterior diameter of medullary canal, 10.5 mm.; lateral, 9 mm. 

 Medullary index, 37%. 



Structure. — The external circumferential lamellae, interrupted by Haversian 

 systems surround the section. The central ring is composed of lamellae and Ha- 

 versian systems. In the anterior wall the toe of the shoe is for the most part 

 displaced by Haversian systems. A wide ring of internal circumferential la- 

 mellae surrounds the medullary canal. In the inner wall the lamellae become 

 laminae. The posterior ridge is composed of elongated Haversian systems. 



Type I-II-III, C. 



* LEFT FEMUR OF A CHICAMA INDIAN. NO. 9, U. S. NAT. MUS.' 



Syn. Tab. IX 



Antero-posterior diameter of bone, 22 mm. ; lateral, 23.5 mm. 

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

 Medullary index, 30%. 



Structure. — A horseshoe of lamellae, laminae, and crude Haversian systems 

 surrounds the section. The toe of the shoe is narrow and the heel wide. 



The central ring is wide and composed of small and large irregularly shaped 

 Haversian systems with short inter-Haversian lamellae, numerous canals, and 

 spaces. 



1 The femora marked (*) have been described, but not drawn. 



