210 SMITHSONIAN CONTKIBUTIONS TO KNOWLEDGE VOL. 35 



BIGHT FEMUK OF A WHITE MALE. NO. 284, CR. MED. COLL. 



Pl. 35, Fig. 445. Syn. Tab. XI 



Antero-posterior diameter of bone, 26.5 mm. ; lateral, 26 mm. 



Antero-posterior diameter of medullary canal, 13 mm.; lateral, 12.5 mm. 



The medullary canal is full. Medullary index, 31 5^. 



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

 the section is a wide horseshoe of crude lamiiife and lamellae, frequently intex*- 

 rupted by Haversian systems of the (la) and (C) differentiations. The horse- 

 shoe forms half of the outer, nearly all of the anterior, and a third of the 

 inner wall. The Haversian systems have, generally, concentric positions. The 

 canals separating the laminae are short. In the inner posterior wall is a fan- 

 shaped area of laminae, interrupted by a few Haversian systems. The remain- 

 der of the central ring, of which the fan is a part, is composed of Haversian 

 systems with some senile changes. In the outer wall it has some inter-Haversian 

 lamellae. The posterior ridge is composed of Haversian systems. 



A narrow ring of internal circumferential lamellae surrounds the medullary 

 canal. 



Type I-II-III, la, C, senile. 



This femur is characterized by units of low differentiations. Only a small 

 portion of it is composed of well developed Haversian systems. 



* EIGHT FEMUR OF A WHITE MALE. NO. 285, CE. MED. COLL. 



Stn. Tab. XI 



Antero-posterior diameter of bone, 29 mm. ; lateral, 28 mm. 



Antero-posterior diameter of medullary canal, 15 mm.; lateral, 1-1 mm. 



The medullary canal is full. Medullary index, 35%. 



Structure. — The external circumferential lamellae are fragmentary. The 

 central ring constitutes nearly all of the section and is composed of Haversian 

 systems with some inter-Haversian lamellae. Manj- senile changes occur around 

 the medullary canal. Internal circumferential lamellae surround the medullary 

 canal. 



Type III, C, senile. 



* EIGHT FEMUR OF A WHITE M.ALE. NO. 286, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 32 mm.; lateral, 27.5 mm. 

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

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



