NO. 3 COMPARATIVE HISTOLOGY OF FEMUR FOOTE 71 



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



AMER. MVS. WAT. HIST. 



Pl. 7. Fig. 101. Syn. Tab ill 



Antero-posterior diameter of boue, 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 l)()ne lias tliree divisions. The exteinal circumferential 

 lamellae form a narrow enclosing ring. Their lacuna" are long and their cana 

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

 versian systems of the (Ic) dift'erentiation. Internal circumferential lamella^ 

 form an uneven rmg around the medullary canal. Their lacunse are long. 



Type I-III, Ic. 



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



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



Antero-jiosterior 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 circuinferential 

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

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

 lacunae, partly displaced by Haversian sj'stems 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 lamellfe have long 

 lacunae and are crossed by numerous canals. 



Type II-III, Ic. 



LEFT FEMUR OF GAVIA 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. Tlie external circum- 

 ferential lamella? form a narrow enclosing ring. The lacuna? 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 lamella? with long lacunse and straight canaliculi surround the 



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