74 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



vol. 35 



Structure. — The section has the three divisions; the external circumfer- 

 ential lamella?, form a narrow ring around the section and have long lacuna 1 

 and straight canaliculi. The central ring is composed of Haversian systems 

 of the (Ic) differentiation between which are canals and short fragments of 

 lamella? with oval lacuna? and bushy canaliculi. The internal circumferential 

 lamella? form a 'distinct, narrow ring around the medullary canal. Their lacuna? 

 are long and canaliculi are straight. 



Type I-ni, Ic. 



RIGHT FEMUR OF ANTHRACOCEROS MALABARICUS. HORN BILL. NO. 2887, 



AMER. MUS. NAT. HIST. 



Pl. 7, Pig. 109. Syn. Tab. Ill 



Antero-posterior diameter of bone, 6.5 mm. ; lateral. 6 mm. 



Antero-posterior diameter of medullary canal, 5.5 mm. ; lateral, 5 mm. 



The medullary canal is empty. Medullary index, 240%. 



Structure. — The section has three divisions. The external circumferential 

 lamella? with long lacuna? and straight canaliculi form a distinct, narrow ring 

 around the bone. The central ring is composed of lamella? with round and 

 oval lacuna?, interrupted by many canals and Haversian systems of the (Ic) 

 stage. The internal circumferential lamella? with long lacuna? form a narrow 

 distinct ring around the medullary canal. 



Type I-III, Ic. 



FEMUR OF ASTUR ATRICAPILLUS. GOSHAWK. CR. MED. COLL. 



Pl. 7, Fig. 110. Syn. Tab. Ill 



Antero-posterior diameter of bone, 4 mm. ; lateral, 4.3 mm. 



Antero-posterior diameter of medullary canal, 3 mm. ; lateral, 3.3 mm. 



The medullary canal is empty. Medullary index, 139%. 



Structure. — The section is surrounded by external circumferential lamella?, 

 fairly well developed. Their lacuna? are more frequently oval than long. The 

 canaliculi are bushy. 



In the inner lateral posterior wall is a slight ridge to which are attached 

 muscle tendons penetrating the external lamella?. Underneath the external 

 circumferential lamella? is a thick ring of Haversian systems of the (Ic) stage of 

 development. The ring is crossed at all angles by wide, irregular canals. 



The medullary canal is enclosed by internal circumferential lamella? with 

 long lacuna? and canaliculi. 



Type I-III, Ic. 



