202 SMITHSONIAN CONTEIBUTIONS TO KNOWLEDGE VOL. 35 



LEFT FEMUE OF A WHITE MALE. NO. 91, CR. MED. COLL. 



Pl. 33, Fig. 418. Syn. Tab. XI 



Antero-posterior diameter of bone, 30 mm. ; lateral, 27 mm. 



Antero-posterior diameter of medullary canal, 17 mm.; lateral, 13 mm. 



The medullary canal is full. Medullary index, 39%. 



Structure. — External circumferential lamellae surround the section, except- 

 ing the posterior ridge. The central ring is composed of Haversian systems 

 with the remains of a laminar horseshoe in the posterior lateral wall. No 

 senile changes are found. 



The internal circumferential lamellae form a narrow ring around the medul- 

 lary canal. 



Type I-II-III, C. 



FEMUR OF AN AUSTR.ALIAN. NO. 227420, U. S. NAT. MUS. 



Pl. 34, Fig. 419. Syn. Tab. XI 



Antero-posterior diameter of bone, 28 mm. ; lateral, 23 mm. 



Antero-posterior diameter of medullary canal, 12 mm.; lateral, 11 mm. 



The medullary canal is full. Medullary index, 25%. 



Structure. — The external circumferential lamellae enclose the bone, except- 

 ing the anterior wall and posterior ridge. Beginning on either side of tlie 

 posterior ridge and extending around the lateral to the anterior wall are two 

 wide bands composed of lamellte and elongated Haversian systems, arranged 

 in concentric rows. Their long diameters are parallel to the external surface 

 of the bone. As the bands approach the anterior wall they are displaced by 

 Haversian sj^stems, which form the whole width of the wall. These bands are 

 the remains of the horseshoe. 



The anterior wall and posterior ridge are composed entirely of Haversian 

 systems. The lacunae are oval and narrow. The internal circumferential la- 

 mellfe form a broken narrow ring around the medullary canal. 



Type I-III, C. 



LEFT FEMUR OF A WHITE MALE. NO. 94, CR. MED. COLL. 



Pl. 34, Fig. 420. Syn. Tab. XI 



Antero-posterior diameter of bone, 30 mm. ; lateral, 29 mm. 



Antero-posterior diameter of medullary canal, 17 mm.; lateral, 14 mm. 



The medullary canal is full. Medullary index, 38%. 



Structure. — External circumferential lamellae form a narrow ring around 

 the section. Beginning on both sides of the posterior ridge and extending 

 around the lateral wall are wide bands of elongated and well developed Ha- 



