88 



SMITHSONIAN CONTBIBUTIONS TO KNOWLEDGE 



VOL. 35 



Structure. — The section is composed of lamellae with oval lacunas and 

 straight canaliculi indistinctly separated into three concentric rings. Incom- 

 plete threefold division. 



Type I. 



BIGHT FEMUR OF PTEBOPUS MOLOSSINUS (LABGE). IT. S. NAT. MUS. 



Pl. 8, Fig. 161. Syn. Tab. IV 



Antero-posterior diameter of bone, 3 mm. ; lateral, 3.5 mm. 

 Antero-posterior diameter of medullary canal, 2.5 mm. ; lateral, 2.5 mm. 

 The medullary canal is full. Medullary index, 147%. 



Structure. — The section is composed of lamellae with long, narrow lacunae 

 and straight canaliculi enclosing the medullary canal. The lamellae are divided 

 into two rings, a narrow external and wide internal. In the inner wall the 

 lamellae are interrupted by a few canals of the (la) differentiation. The femur 

 shows a little advancement. Twofold division. 



Type I-III, la. 



BIGHT FEMUK OF PTEBOPUS ALDABBENSIS. NO. 20989, U. S. NAT. MUS. 



Pl. 8. Fig. 162. Syn. Tab. IV 



Antero-posterior diameter of bone, 2 mm. ; lateral, 2.5 mm. 

 Antero-posterior diameter of medullary canal, 1 mm. ; lateral, 1.5 mm. 

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



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

 long lacunae and straight canaliculi interrupted by a few crude, undeveloped Ha- 

 versian systems of the (la) differentiation. 



Type I-III, la, 



BIGHT FEMUR OF PTEBOPUS. (CELEBES.) NO. 172460, U. S. NAT. MUS. 



Pl. 8, Fig. 163. Syn. Tab. IV 



Antero-posterior diameter of bone, 4 mm. ; lateral, 3.5 mm. 

 Antero-posterior diameter of medullary canal, 2.5 mm. ; lateral, 2 mm. 

 The medullary canal is full. Medullary index, 55%. 



Structure. — The section is composed of a wide external band of lamellae 

 divided into two nearly equal concentric rings by longitudinal canals of the (la) 

 differentiation. The lacunae are oval and narrow and the canaliculi are straight. 

 Internal circumferential lamellae with long lacunae and straight canaliculi sur- 

 round the medullary canal. 



Type I-III, la. 



