158 SMITHSONIAN CONTEIBUTIONS TO KNOWLEDGE VOL. 35 



Structure. — The external circumferential lamellae are fragmentary. Be- 

 ginning on the outer side of the posterior ridge and extending around the 

 external half of the outer wall is a wide baud of alternating laminae and Ha- 

 versian systems. Underneath the band is a central ring of Haversian systems. 

 The anterior, inner, and posterior wall is composed almost entirely of Haversian 

 systems. The internal circumferential lamellae form a narrow, enclosing ring 

 around the medullary canal. 



Type I-II-III, C. 



LEFT FEMUE OF A NEGEO. NO 56, MED. DEPT. TULANE UNIV. 



Pl. 23, Fig. 319. Syn. Tab. VIII 



Antero-posterior diameter of bone, 27.5 mm.; lateral, 27 mm. 



Antero-posterior diameter of medullary canal, 16 nam.; lateral, 14 mm. 



The medullary canal is full. Medullary index, 43%. 



Structure. — The external circumferential lamellae are fragmentary. The 

 central ring is composed of a wide band of lamellae with Haversian systems 

 in the outer and anterior wall and of Haversian systems with some inter- 

 Haversian lamelte in the inner and posterior wall. The systems are well de- 

 veloped but senile to a great extent. Tlie internal circumferential lamellae are 

 fragmentary. 



Type I-III, C, senile. 



LEFT FEMUR OF A NEGEESS. NO. 220, CE. MED. COLL. 



Pl. 23, Fig. 320. Syn. Tab. VIII 



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



Antero-posterior diameter of medullary canal, 18 mm.; lateral, 14 mm. 



The medullary canal is full. Medullary index, 50%. 



Structure. — A wide circumferential horseshoe band of lamellae forms the 

 background of the section. It is narrowest in the inner, forms two-thirds of 

 the anterior, and over half of the outer wall. In these situations the lamellae 

 are to some extent displaced by Haversian systems of the (la) and (C) differen- 

 tiations. The central ring is narrow and is composed of Haversian systems, 

 many of which are senile. There are relatively few cross canals. The internal 

 circumferential lamellae form a narrow ring which becomes cancellous. 



Type I-III, la, C, senile. 



RIGHT AMPUTATED FEMUE OF A NEGRESS. NO. 220, CR. MED. COLL. 



Pl. 23, Fig. 321. Syn. Tab. VIII 



The femur is amputated at lower third. 



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



