174 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



vol. 35 



The internal circumferential lamellae surround the medullary canal. They 

 expand in both lateral walls into two wide crescents composed of wide lamellar 

 bands and crossed by numerous canals from the medullary surfaces. The 

 lacunae of all parts are oval. 



Type II-III, la, C. 



* LEFT FEMUR OF AN ADOLESCENT PACHACAMAC INDIAN. NO. 8, U. S. NAT. MUS. 



Syn. Tab. IX 



Antero-posterior diameter of bone, 22.5 mm. ; lateral, 18 mm. 

 Antero-posterior diameter of medullary canal, 9 mm. ; lateral, 7 mm. 

 Medullary index, 19%. 



Structure. — The remains of the external horseshoe of lamellae are evident. 

 In this section the lamellae are separated into laminae which are interrupted by 

 frequent Haversian systems. 



The central ring is wide and composed of well developed Haversian sys- 

 tems with very little inter-Haversian lamellae. There are many canals running 

 in various directions. 



A narrow ring of internal circumferential lamella? encloses the medullary 

 canal. The lacunae are oval and round. 



Type II-III, C. 



* RIGHT FEMUR OF A PACHACAMAC INDIAN CHILD. NO. 11, U. S. NAT. MUS. 



Syn. Tab. IX 



Antero-posterior diameter of bone, 10 mm. ; lateral, 9 mm. 

 Antero-posterior diameter of medullary canal, 7 mm.; lateral, 6.5 mm. 

 Medullary index, 100%. 



Structure. — The section is composed of lamellae and laminae in the form 

 of a horseshoe embracing the posterior ridge. The shoe is crossed by canals 

 and interrupted by Haversian systems which are developing from the vascular 

 canals. The lacunae are oval and round. The posterior ridge is composed of 

 developing Haversian systems, between which are coarse canaliculi and large, 

 round lacunae embedded in bone substance. The ridge is distinctly marked off 

 from the enclosing laminae. 



Type II-III, la, lb. 



LEFT FEMUR OF A PACHACAMAC INDIAN CHILD. NO. 12, U. S. NAT. MUS. 



Pl. 27, Fig. 357. Syn. Tab. IX 



Antero-posterior diameter of bone, 10 mm.; lateral, 12.5 mm. 

 Antero-posterior diameter of medullary canal, 7 mm.; lateral, 7.5 mm. 

 Medullary index, 72%. 



