168 SMITHSONIAN CONTBIBUTIONS TO KNOWLEDGE VOL. 35 



BIGHT FEMUR OF A PUEBLO INDIAN CHILI), SIX YEAKS OLD. NO. 258675(L), 



U. S. NAT. MUS. 



Pl. 25, Fig. 342. Syn. Tab. IX 



Antero-posterior diameter of bone, 12 mm.; lateral, 10.5 mm. 



Antero-posterior diameter of medullary canal, 8 mm.; lateral, 6 mm. 



The medullary canal is full. Medullary index, 61%. 



Structure. — Beginning on both si<les of the posterior ridge and extending 

 around the section is a horseshoe-shaped band of laminte and lamellfe, inter- 

 rupted by Haversian systems of the (la) dilTerentiation. In the inner wall the 

 band is composed of lamiuje, separated by rather short, wide canals. The 

 laminae gradually merge into a narrow band of lamellae as they pass around 

 the inner lateral into the anterior wall. The band of lamella^ then widens in 

 the outer wall and separates into laminae, which form the whole width of the 

 wall just before reaching the posterior ridge. The lacunae are oval. 



Underneath this band is a central ring of large, small, and irregularly 

 shaped Haversian systems with inter-Haversian lamellae. Many large canals 

 occur which are irregular in shape and surrounded by clear areas of bone 

 substance with few oval lacunae. The systems communicate by canals which, 

 in some portions, assume the form of a network. The ring reaches the external 

 surface of the posterior ridge. 



The internal circumferential lamellfe surround the medullary canal, except- 

 ing in the outer posterior wall where the systems form the border of the canal. 



Type I-II-III, la, C. 



LEFT FEMUK OF A PUEBLO INDIAN, TWELVE YEAKS OLD. NO. 258675(82), 



U. S. NAT. MUS. 



Pl. 25, Ki(!. .312*. Svn. 'I'ab. I X 



Antero-posterior diameter of lioiic, 17 nun.; lateral, l(i nmi. 



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



The medullary canal is full. Medullary index, 42%. 



Striictvre. — Around the outside of the section is a horseshoe-shaped band 

 of lamellae, separated into fragmentary laminae by short concentric canals. The 

 toe of the shoe is the widest part of tiie band and the heel of the inner is wider 

 than that of the outer wall. The band is frequently interrupted by spaces of 

 various sizes and shapes, the significance of which is not clear, and by Ha- 

 versian systems of the (la) differentiation. The spaces are generally visible 

 to the naked eye, and some of them are surrounded by clear areas crossed by a 

 few canaliculi. 



Underneath the horseshoe band is a central ring of incomplete Haversian 

 systems with intervening lamelhi?. The ring is also frequently interrupted 



