42 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



vol. 35 



EIGHT FEMUR OF RANA AREOLATA CIRCULOSA. NO. F 72 3, U. S. NAT. MUS. 



Pl. 2, Fig. 21. Syn. Tab. I 



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

 Antero-posterior diameter of medullary canal, 1.5 mm. ; lateral, 1.4 mm. 

 The medullary canal is full. Medullary index, 110%. 



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

 and bushy canaliculi surrounding the medullary canal. The bone is uniform in 

 structure. A portion of tlie nutrient canal is seen. 



Type I. 



RIGHT FEMUR OF RANA AGILIS AURORA. NO. F 50 10, U. S. NAT. MUS. 



Pl. 2. Fig. 22. Syn. Tab. I 



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

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

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



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

 straight canaliculi surrounding the medullary canal, and divided into dim, wide 

 external and narrow internal rings. Twofold division. 



Type I. 



RIGHT FEMUR OF RANA PKETIOSA. NO. F 75 11, U. S. NAT. MUS. 



Pl. 2. Fig. 23. Syn. Tab. I 



Antero-posterior diameter of bone, 2 mm. ; lateral, 1.5 mm. 

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

 The medullary canal is full. Medullary index, 41%. 



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

 and bushy canaliculi, dimly separated into four or five concentric divisions. 

 In some portions of the section a few radiating canals are seen. 



Type I. 



RIGHT FEMUR OF RANA DRAYTONII. NO. F 70 14, U. S. NAT. MUS. 



Pl. 2. Fig. 84. Syn. Tab. I 



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

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

 The medullary canal is full and eccentrically situated. Medullary index, 

 33%. 



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

 and bushy canaliculi surrounding the medullary canal. The lacunae are gen- 

 erally arranged in concentric rows and their bushy canaliculi extend outward 



