170 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 35 



with tlie external surface of tlie bone. The internal circumferential lamella; 

 surround the medullary canal. Their lacuna? are long. 

 Type III, C. 



LEFT FEMUR OF A PERUVIAN INDIAN. NO. li66469( 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- 

 melliB. The inner wall is extended in the fonn of a ridge and is composed of 

 lamiiuv 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 circuraferential lamellae form an irregular ring around the 

 medullary canal. In some jilaces the lamella? are indistinctly separated into 

 laminae. 



Type I-II-III, C, senile. 



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



Pl. 26, Fig. 346. Stn. 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, wliile a very i)rominent heavy ridge occurs 

 in the inner wall. Tliis gives to the bone a ])eculiar shape. 



Tlie me(hillary canal is full. Medullary index, 36'/, . 



Striu-fure. — The external circumferential lamellae are fragmentary. The 

 section is composed almost entirely of well developed Haversian systems with 

 some inter-Haversian lamella\ 



The internal ciicumferential laniell;v are fragmentary. 



Type III, C. 



LEKT FEMl'K 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 lamellie, 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 



