170 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



vol. 35 



with the external surface of the bone. The internal circumferential lamellae 



surround the medullary canal. Their lacunae are long. 

 Type III, C. 



LEFT FEMUR OF A PERUVIAN INDIAN. NO. 266469(b), U. S. NAT. MUS. 



Pl. 26, Fig. 345. Syn. Tab. IX 



Antero-posterior diameter of bone, 27 mm. ; lateral, 31 mm. 

 Antero-posterior diameter of medullary canal, 21 mm.; lateral, 19 mm. 

 The medullary canal is full. Medullary index, 91%. 



Structure. — The section is surrounded by a narrow ring of external la- 

 mella?. The inner wall is extended in the form of a ridge and is composed of 

 lamina?, parallel with the ridge surface. The laminae are perforated by irregu- 

 larly shaped spaces. The central ring is wide and composed of well developed 

 Haversian systems, many of which are senile, especially those of the outer wall. 



The internal circumferential lamellae form an irregular ring around the 

 medullary canal. In some places the lamellae are indistinctly separated into 

 laminae. 



Type I-II-ni, C, senile. 



LEFT FEMUR OF A PERUVIAN INDIAN. NO. 266469(a), U. S. NAT. MUS. 



Pl. 26, Fig. 346. Syn. Tab. IX 



Antero-posterior diameter of bone, 22 mm. ; lateral, 27 mm. 

 Antero-posterior diameter of medullary canal, 13 mm. ; lateral, 12 mm. 

 The posterior ridge is small, while a very prominent heavy ridge occurs 

 in the inner wall. This gives to the bone a peculiar shape. 

 The medullary canal is full. Medullary index, 36%. 



Struct are. — The external circumferential lamellae are fragmentary. The 

 section is composed almost entirely of well developed Haversian systems with 

 some inter-Haversian lamellae. 



The internal circumferential lamellae are fragmentary. 



Type III, C. 



LE FT FEMUR OF A CHICAMA INDIAN. NO 2, U. S. NAT. MUS. 



Pl. 26, Fig. 347. Syn. Tab. IX 



Antero-posterior diameter of bone, 31 mm. ; lateral, 30 mm. 



Antero-posterior diameter of medullary canal, 13 mm.; lateral, 13 mm. 



The walls of the bone are thick. Medullary index, 22%. 



Structure. — A wide horseshoe of lamellae, interrupted by Haversian systems 

 of the (la) differentiation surrounds the section. The central ring, composed 

 of large, small, and irregularly shaped Haversian systems, constitutes nearly 



