164 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 35 



outer half is composed of well developed Haversian systems between narrow 

 external and internal circumferential lamellae. 

 Type I-III, la, C. 



Eeviewiug the long bones of this negro, No. 248674, it may be observed 

 that they all conform to the first and third or first, second, and third types of 

 structure, whicli types must be considered basic for this individual. 



LEFT FEMUR OF A NEGRO. NO. 224713, U. S. NAT. MUS. 



Pl. 24, Fig. 334. Syn. Tab. VIII 



Antero-posterior diameter of bone, 35 mm. ; lateral, 24 mm. 



Anteroposterior diameter of medullary canal, 20 mm. ; lateral, 12 mm. 



The medullary canal is full; cancellous bone is prominent in the posterior 

 wall. Medullary index, 40%. 



Structure. — The section is surrounded by a more or less fragmentary ring 

 of lamellae, laminae, and Haversian systems. The ring is wide and broken by 

 Haversian systems of the central ring in the posterior and inner wall. The 

 central ring is composed of well developed Haversian systems and inter-Ha- 

 versian lamellae. Internal circumferential lamelljE form a narrow ring around 

 the medullary canal. 



Type I-II-III, la, C. 



BIGHT FEMUR OF A NEGRO. NO. 83, MED. DEPT. TULANE VNIV. 



Pl. 25, FiG. 335. Syn. Tab. VIII 



Antero-posterior diameter of bone, 30 mm.; lateral, 25 nun. 



Antero-posterior diameter of medullary canal, 12 mm.; lateral, 10 nun. 



The medullary canal is full. Medullary index, 19%. 



Structure. — Beginning on both sides of the posterior ridge and extending 

 around the section is a horseshoe of lamelLns, laminas, and Haversian systems 

 of the (la) and (C) differentiations. It is thin in the outer and thick in the 

 remaining wall. The central ring is irregular and incomplete and composed 

 of well developed Haversian systems with long, narrow lacunae and straight 

 canaliculi. Tlie internal circumferential lamellae form a very irregular ring, 

 which, in the outer wall, spreads out into a curved, fan-shaped area of laminae 

 occupying most of that wall. The leaves of the fan then merge into a wide 

 band of lamellae, which bends inward to the medullary surface of the anterior 

 wall. The fan encloses several complete Haversian systems and short canals. 



Type I-II-III, la, C. 



