NO. 3 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 



41 



RIGHT FEMUR OF CHOROPHILUS FERIARUM. NO. E 52 47, U. S. NAT. MUS. 



Pl. 2, Fig. 17. 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 lamellae with oval lacunas and 

 straight canaliculi, divided into wide external and narrow internal rings. The 

 internal ring forms the internal circumferential lamellae. Twofold division. 



Type I. 



RIGHT FEMUR OF ACRIS GRYLLUS. U. S. NAT. MUS. 



Pl. %, Fig. 18. Syn. Tab. I 



Antero-posterior diameter of bone, 0.5 mm. ; lateral, 0.3 mm. 

 Antero-posterior diameter of medullary canal, 0.2 mm. ; lateral, 0.1 mm. 

 The medullary canal is full. Medullary index, 16%. 



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

 straight canaliculi, divided into wide external and narrow internal rings. The 

 internal ring forms the internal circumferential lamellae. Twofold division. 



Type I. 



RIGHT FEMUR OF RANA CATESBIANA. BULL FROG. AMER. MUS. NAT. HIST. 



Pl. 2. Fig. 19. Syn. Tab. I 



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

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

 The medullary canal is full. Medullary index, 56%. 



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

 lacunae and straight, long, thickly set canaliculi, arranged concentrically around 

 the medullary canal. The bone is uniform. 



Type I. 



RIGHT FEMUR OF RANA PALUSTRIS. NO. F 52 22, U. S. NAT. MUS. 



Pl. 2. Fig. 20. Syn. Tab. I 



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

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

 The medullary canal is full. Medullary index, 44%. 



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

 oval lacunae and bushy canaliculi, separated into two concentric rings. The 

 positions of the lacunae and canaliculi give a radiating effect, The internal 

 ring forms the internal circumferential lamellae. Twofold division. 



Type I. 



