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SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 35 



terior wall the canals are circular in cross-section, elsewhere they are long. The 

 bone shows a little differentiation of structure. 

 Type I-III, la. 



RIGHT FEMUR OF HELODERMA SUSPECTUM. GILA MONSTER. NO. 583, 



AMER. MUS. NAT. HIST. 



Pl. 4, Fig. 50. Syn. Tab. II 



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

 Antero-posterior diameter of medullary canal, 0.7 mm.; lateral, 0.7 mm. 

 The medullary canal is full. Medullary index, 5%. 



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

 long lacunae with bushy and straight canaliculi indistinctly outlined in laminae. 

 The external lamellae show long lacunae and rather straight canaliculi, the re- 

 maining lamellae, oval lacunae and bushy canaliculi. Around the medullary 

 canal is an enclosing ring of lamellae with lacunae and long, straight cana- 

 liculi. The bone shows traces of differentiation into the three main divisions 

 —external, a central ring, and internal circumferential lamellae. There is no 

 trace of an Haversian system. 



Type I. 



RIGHT FEMUR OF SGELOPORUS CLARKII. NO. I 61 17, U. S. NAT. MUS. 



Pl. 4, Fig. 51. Syn. Tap.. II 



Antero-posterior diameter of bone, 1.5 mm. ; lateral, 1.5 mm. 



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



The medullary canal is full. Medullary index, 12%. 



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

 and bushy canaliculi surrounding the medullary canal. There is no differentia 

 tion of structure. The section is uniform. 



Type I. 



RIGHT FEMUR OF SCELOPORUS SPINOSUS FLORIDANUS. NO. I 73 12, 



U. S. NAT. MUS. 



Pl. 4. Fig. 52. Syn. T.ab. II 



Antero-posterior diameter of bone, 1.5 mm. ; lateral, 1.5 mm. 

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

 The medullary canal is full. Medullary index, 12%. 



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

 and straight canaliculi surrounding the medullary canal. There is no dif - 

 ferentiation of structure. The section is uniform. 



Type I. 



