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SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 35 



the anterior and an area of Haversian systems in the posterior wall. A single 

 concentric lamina divides the section into two parts. Each lamina is composed 

 of a few lamella? with well developed lacuna' and canaliculi. There is a crescent 

 of well developed Haversian systems in the anterior wall bordering upon the 

 internal circumferential lamellae. The posterior wall is composed of well de- 

 veloped Haversian systems extending from the external surface of the bone to 

 the internal circumferential lamella?. A narrow ring of internal circumferential 

 lamellae with long lacunae and straight canaliculi surrounds the medullary canal. 

 Type II-III, C. 



FEMUR OF CEPHALOPHUS AFRICAN ANTELOPE. NO. 163255, U. S. NAT. MUS. 



Pl. 18, Fig. 273. Syn. Tab. VII 



Antero-posterior diameter of bone, 15 mm.; lateral, 13.5 mm. 

 Antero-posterior diameter of medullary canal, 9 mm. ; lateral, 9 mm. 

 The medullary canal is full. Medullary index, 67%. 



Structure. — The bone is composed of a wide horseshoe band of laminae 

 embracing the posterior ridge. The laminae are long and short and are inter- 

 rupted by a few Haversian canals in the external laminae. They are crossed by 

 numerous canals from the medullary canal. Their lacunae are long and their 

 canaliculi are straight. Underneath the lamina? and adjacent to the internal 

 circumferential lamellae is a narrow ring of Haversian systems. The systems 

 form nearly the whole posterior ridge, and elsewhere are situated between the 

 canals extending outward from the medullary canal. They are well developed. 

 The medullary canal is surrounded by a narrow ring of internal circumferen- 

 tial lamellae well developed. 



Type II-III, C. 



FEMUR OF RAPHICEROS. STEINBOK. NO. 164801, U. S. NAT. MUS. 



Pl. 18, Fig. 274. Syn. Tab. VII 



Antero-posterior diameter of bone, 12 mm.; lateral, 12.5 mm. 

 Antero-posterior diameter of medullary canal, 6.5 mm. ; lateral, 7 mm. 

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



Structure. — The section is surrounded by a narrow ring of lamellae and 

 Haversian systems. In the posterior lateral wall is a group of Haversian 

 systems which forms nearly the whole wall. The lacuna? are long and their 

 canaliculi bushy and straight. The remainder of the bone is composed of la- 

 minae, crossed at various angles by canals and interrupted here and there by 

 very crude Haversian systems of the (la) differentiation. The lacunae are long 

 and narrow. 



Type II-III, la, C. 



