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SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 35 



internal circumferential lamellae with long lacunae and straight canaliculi form 

 a narrow ring around the medullary canal. 

 Type II-III, Ic. 



EIGHT FEMUR OF CYAN OCTTTA CRISTATA. BLUE JAY. CK. MED. COLL. 



Pl. 5, Fig. 78. Syn. Tab. Ill 



Antero-posterior diameter of bone, 2.5 mm. ; lateral, 2.5 mm. 

 Antero-posterior diameter of medullary canal, 1.5 mm. ; lateral, 1.5 mm. 

 The bone is nearly round. The medullary canal is full. Medullary index, 

 56%. 



Structure. — The section is composed of bone substance separated into crude 

 laminae by short, branching, more or less concentric canals. A few Haversian 

 systems of the (Ic) stage of differentiation appear here and there. The lacunae 

 are oval and the canaliculi are short and bushy. 



Type II-III, Ic. 



LEFT FEMUR OF PTEROGLOSSUS TORQUATUS. BANDED TOUCAN. NO. 2854, 



AMER. MUS. NAT. HIST. 



Pl. 5, Fig. 79. Syn. Tab. Ill 



Antero-posterior diameter of bone, 3 mm. ; lateral, 3 mm. 

 Antero-posterior diameter of medullary canal, 2 mm. ; lateral, 2 mm. 

 The medullary canal is full. Medullary index, 80%. 



Structure. — The section is composed of concentric lamellae with oval lacunae 

 and bushy canaliculi, crossed by a few short canals surrounding the medullary 

 canal. 



Type I. 



LEFT FEMUR OF CHARADRIUS PLUVIALIS. GOLDEN PLOVER. NO. 3356, 



AMER. MUS. NAT. HIST. 



Pl. 5, Fig. 80. Syn. Tab. Ill 



Antero-posterior diameter of bone, 2.5 mm.; lateral, 2.5 mm. 

 Antero-posterior diameter of medullary canal, 1.5 mm. ; lateral, 1.5 mm. 

 The medullary canal is full. Medullary index, 56%. 



Structure'. — The section is composed of concentric lamellae with oval lacunae 

 and bushy canaliculi, interrupted by a few crude Haversian systems. The la- 

 mellae are partially separated into laminae by short concentric canals. The bone 

 shows little differentiation. 



Type II. 



