38 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 35 



RIGHT FEMUR OF AMBLYSTOMA TIGRINUM. AMER. MUS. NAT. HIS. 



Pl. 2, Fig. G. Syn. Tab. I 



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

 Antero-posterior diameter of medullary canal, cancellous meshes. 

 Medullary index, 0. 



Structure. — The section has no distinct medullary canal. It is composed 

 of a narrow external ring of bone substance, with a few oval lacunae and bushy 

 canaliculi, from the under portion of which a cancellous center is derived. The 

 meshes are filled with structureless material, and their walls have the same 

 structure as the walls of the bone. 



Type I. 



RIGHT FEMUR OF HYLA VERSICOLOR. TREE FROG. AMER. MUS. NAT. HIST. 



Pl. 2, Fig. 7. Syn. Tab. I 



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

 Antero-posterior diameter of medullary canal, 0.2 mm. ; lateral, 0.2 mm. 

 The medullary canal is full. Medullary index, 7%. 



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

 lacunas and bushy canaliculi enclosing the medullary canal. The section has 

 a uniform structure. 



Type I. 



RIGHT FEMUR OF HYLA ARENICOLOR, NO. E 50 30, U. S. NAT. MUS. 



Pl. 2. Fig. 8. Syn. Tab. I 



Antero-posterior diameter of bone, 0.5 mm.; lateral, 0.5 mm. 

 Antero-posterior diameter of medullary canal, 0.2 mm.; lateral, 0.2 mm. 

 The medullary canal is full. Medullary index, 19%. 



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

 and long, straight canaliculi, divided into wide external and narrow internal 

 rings which surround its medullary canal, thus showing a twofold division. 



Type I. 



RIGHT FEMUR OF HYLA FEMORALIS. NO. E 60 23, ~U. S. NAT. MUS. 



Pl. 2, Fig. 9. Syn. Tab. I 



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

 Antero-posterior diameter of medullary canal, 0.2 mm. ; lateral, 0.2 mm. 

 The medullary canal is full. Medullary index, 24%. 



Structure. — The section is composed of concentric lamellse with oval lacuna? 

 and long canaliculi, divided into wide external and narrow internal rings which 

 surround the medullary canal, a twofold division. 



Type I. 



