172 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 35 



Structure. — Beginning on tlie ontcr side of tlie posterior ridge is a wide 

 band of lamella- in which arc 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 lamellae so often present in the lower types of bone. The 

 posterior ridge is composed of small, irregularly shaped Haversian systems 

 with inter-Haversian lamellse. 



A narrow band of internal circumferential lamellae surrounds the medullary 

 canal. 



Type I-III, C, senile. 



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



Pl. 27, Fifi. 351. Syn. Tab. TX 



Antero-posterior diameter of l)one, 18.5 mm.; hiteral, 111 mm. 



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



Medullai'v index, 37%. 



Stiucture. — The extei'nal circiunferential lamella-, interrupted by Haversian 

 systems surround tlie 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- 

 inelliB surrounds the medullary canal. In the inner wall the lamellfe become 

 laminae. The posterior ridge is composed of elongated Haversian s.ystems. 



Tyi)e I-II-III, C. 



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



Syn. Tab. IX 



Aiitcro-itosterior diainetcr ol' bone, L'L' mm.; lateral, 23.5 mm. 



Aiitcro posterioi' diampjcr of iiiediillary canal, 11 iniii.; lateral, 11 nun. 



M.'dullary index, 30%. 



St met ure.- A horseshoe of lamella^, lamina\ and crude Haversian systems 

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



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

 llaveisiaii systems with short inter-Haversian lamelhe, numerous canals, and 

 spaces. 



'Tlie femora marked (*) liave been described, but not drawn. 



