xo. 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 49 



vascular canal appears in the inner and posterior wall. There is very little 

 dilt'erentiation of structure. The bone is uniform. 

 Type I. 



EIGHT FEMUR OF PHRVXOSOMA CORNUTUM. TEXAS HORNED TOAD. XO. lliUO, 



AMER. MUS. NAT. HIST. 



Pl. 3, Pig. -II. Syx. Tab. II 



Autero-posterior diameter of bone, '2.H mm.; lateral, 1.5 nun. 



Antero-posterior diameter of medullary canal, 0.8 mm.; lateral, U.5 mm. 



The medullary canal is full. Medullary index, 10%. 



Structure. — The section is composed of concentric lamelkc with long and 

 oval lacunae aud straight aud bushy canaliculi surrounding the medullary canal. 

 The lacunie of the external portion are long aud narrow with straight canaliculi, 

 and those of the medullary portion are oval with bushy canaliculi. There is 

 very little differentiation of structure. The section shows an indistinct twofold 

 division. 



Type I. 



LEFT FEMUR OF CHAM.ffiLE0 VULGABIS. CHAMELEON. XO. 135, AMER. MUS. XAT. HIST. 



Pl. 3, Fig. 42. Syx. Tab. II 



Autei-o-posterior diameter of bone, 1.8 mm.; lateral, 1.5 nmu 



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



The medullary canal is full. Medullary index, 42%. 



Structure. — The section is composed of an external ring of lamellae with 

 oval lacuna? and bushy canaliculi. The lacunse tend to flatten as they reach the 

 external surface. In the posterior wall the lacunae are large aud nearly round. 

 Underneath this ring is another of lamellae with oval lacuna? and bushy canali- 

 culi. The two rings are separated by concentric, central lacunae closely packed 

 together. The bone shows an indistinct twofold division. 



Type I. 



RIGHT FEMUR OF PHRVXOSOMA DOUGL-iSSH. X^O. L 50 12, U. S. SAT. MUS. 



Pl. 3. Fig. 43. Syx. Tab. II 



Antero-posterior diameter of bone, 2 mm.; lateral, 1 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 long canaliculi surrounding the medullary canal. Little or no dilTerentia- 

 tion has occurred. The section has a uniform structure. 



Type I. 



