NO. 3 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 



43 



from them. The eanalieuli frequently unite and form a fine network. In some 

 parts of the section there are large radiating- canals extending the whole width 

 of the walls of the bone. These canals communicate with adjacent lacunae by 

 fine eanalieuli. The section as a whole has a bushy appearance. The large 

 radiating canals seem to be found only in the frogs of large size. 

 Type I. 



RIGHT FEMUR OF SPELERPES RUBER. RED SALAMANDER. AMER. MUS. NAT. HIST. 



Pl. 2. Fig. 25. Syn. Tab. I 



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

 Antero-posterior diameter of medullary canal, 0.3 mm.; lateral, 0.2 mm. 

 The medullary canal is full. Medullary index, 4%. 



Structure. — The entire section is composed of lamella' with elongated 

 lacuna 1 and bushy eanalieuli enclosing the medullary canal. The bone has a 

 uniform structure. 



Type I. 



RIGHT FEMUR OF CR VPTOBRANCHUS ALLEGHENIENSIS. HELLBENDER. 

 AMER, MUS. NAT. HIST. 



Pl. 2, Fig. 26. Syn. Tab. I 



Antero-posterior diameter of bone, 2.5 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, 7%. 



Structure. — With the exception of a few lamellae around the medullary 

 canal the entire section is composed of round and oval lacuna? with bushy eana- 

 lieuli embedded in bone substance and arranged concentrically around the 

 medullary canal. The medullary canal is relatively small. A slight structural 

 differentiation appears in the lamellae around the medullary canal. Twofold 

 division. 



Type I. 



RIGHT FEMUR OF NECTURUS MACULATUS. AMER. MUS. NAT. HIST. 



Pl. 2, Fig. 27. Syn. Tar. I 



Antero-posterior diameter of bone, 2 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, 9%. 



Structure. — Around the section are a few enclosing lamella? with rather 

 long lacuna 1 . Nearly the entire section is composed of large, oval, round, and 

 elongated lacuna? with bushy eanalieuli arranged radially between enclosing 

 lamellae. The arrangement of the lacuna? is such as to give a radiating appear- 



