50 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 35 



RIGHT FEMUR OF PTYCHOZOON HOMALOCEPHALUM GECKO. NO. 684 



AMER. MUS. NAT. HIST. 



Pl. 3, Fig. 44. Syn. Tab. II 



Antero-posterior diameter of bone, 1 mm. ; lateral, 0.8 mm. 

 Antero-posterior diameter of medullary canal, 0.5 mm.; lateral, 0.4 mm. 

 The medullary canal is full. Medullary index, 33%. 



Structure. — The section is composed of concentric lamellae with long lacuna? 

 and long', straight canaliculi surrounding the medullary canal. Very little dif- 

 ferentiation appears. The section is uniform. 



Type I. 



RIGHT FEMUR OF IGUANA TUBERCULATA. AMER. MUS. NAT. HIST. 



Pl. 3. Fig. 45. Syn. Tab. II 



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

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

 The medullary canal is full. Medullary index, 61%. 



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

 and long, straight canaliculi surrounding the medullary canal. The posterior 

 wall is thickest and shows a column of oval lacunae and their lamellae extending 

 from the medullary canal toward the external posterior surface. Very little 

 differentiation of structure appears. The section is uniform. 



Type I. 



LEFT FEMUR OF VARANUS SALVATOR. AMER. MUS. NAT. HIST. 



Pl. 3. Pig. 46. Syn. Tab. II 



Antero-posterior diameter of bone, 11 mm.; lateral, 10 mm. 

 Antero-posterior diameter of medullary canal, 7 mm. ; lateral, 6 mm. 

 The medullary canal is full. Medullary index, 51%. 



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

 oval lacunae and bushy canaliculi surrounding the bone, with the exception of 

 the posterior wall. The lamellae are partially separated into laminae by con- 

 centric rows of long lacunae placed end to end. Numerous short canals, parallel 

 to each other and radiating from the medullary canal, cross the lamellae. Around 

 the canals are clear areas of bone substance crossed in many instances by fine 

 canaliculi. In the posterior and inner wall the concentric lamellae are displaced 

 by canals and oval lacunae with bushy canaliculi extending from the external 

 surface to the medullary canal. The canals mark the locations of future Ha- 

 versian systems. Fragments of lamellae surround the medullary canal. In the 



