NO. 3 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 



71 



RIGHT FEMUR OF SARCORHAMPHUS GRYPHUS. ANDEAN CONDOR. NO. 1276, 



AMER. MUS. NAT. HIST. 



Pl. 7, Fig. 101. Syn. Tab. Ill 



Antero-posterior diameter of bone, 18.5 mm. ; lateral, 17.5 mm. 

 Antero-posterior diameter of medullary canal, 15 mm. ; lateral, 14.5 mm. 

 The medullary canal is full. Medullary index, 204%. 



Structure. — The bone lias three divisions. The external circumferential 

 lamellae form a narrow enclosing; ring. Their lacunae are long and their cana- 

 liculi are straight. The central ring is composed of round and elongated Ha- 

 versian systems of the (Ic) differentiation. Internal circumferential lamella' 

 form an uneven ring around the medullary canal. Their lacuna? are long. 



Type I-III, Ic. 



RIGHT FEMUR OF OLOR SP. SWAN. NO. 1681, AMER. MUS. NAT. HIST. 



Pl. 7. Fig. 102. Syn. Tab. Ill 



Antero-posterior diameter of bone, 11.5 mm.; lateral, 10.5 mm. 

 Antero-posterior diameter of medullary canal, 7 mm.; lateral, 8 mm. 

 Medullary index, 87%. 



Structure.- — The bone has the three divisions. The external circumferential 

 lamellae form a narrow enclosing ring. Their lacunae are long and their cana- 

 lieuli are straight. The central ring is composed of crude laminae with oval 

 lacunae, partly displaced by Haversian systems of the (Ic) differentiation. In 

 the anterior inner wall indistinct laminae appear. A wide ring of lamellae, partly 

 separated into laminae, surrounds the medullary canal. The lamella? have long 

 lacunae and are crossed by numerous canals. 



Type II III, Ic. 



LEFT FEMUR OF G A VI A STELLATA. RED-THROATED LOON. NO. 2801, 

 AMER. MUS. NAT. HIST. 



Pl. 7. Fig. 103. Syn. Tab. Ill 



Antero-posterior diameter of bone, 8.5 mm. ; lateral, 6.5 mm. 



Antero-posterior diameter of medullary canal, 5 mm. ; lateral, 4 mm. 



The medullary canal is divided into two equal parts, antero-posteriorly by 

 a partition of bone. Medullary index, 184%. 



Structure. — The section has the three divisions. The external circum- 

 ferential lamellae form a narrow enclosing ring. The lacunae are long and oval 

 and their canaliculi are long and bushy. The central ring is composed of 

 lamellae and Haversian systems of the (Ic) differentiation. The internal cir- 

 cumferential lamellae with long lacunae and straight canaliculi surround the 



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