NO. 3 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 



49 



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

 differentiation of structure. The bone is uniform. 

 Type T. 



right femur of p.heynosoma cornutum. texas horned toad. no. 1200, 



amer. mus. nat. hist. 



Pl. 3, Pig. 41. Syn. Tar. 11 



Antero-posterior diameter of bone, 2.8 mm.; lateral, 1.5 mm. 

 Antero-posterior diameter of medullary canal, 0.8 mm.; lateral, 0.5 mm. 

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



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

 oval lacunas and straight and bushy canaliculi surrounding the medullary canal. 

 The lacunae of the external portion are long and 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 CHAMiELEO VULGARIS. CFIAMELEON. NO. 135, AMER. MUS. NAT. HIST. 



Pl. 3, Pig. 42. Syn. Tar. II 



Antero-posterior diameter of bone, 1.8 mm. ; lateral, 1.5 mm. 

 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 lamella? with 

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

 external surface. In the posterior wall the lacunas are large and nearly round. 

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

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

 together. The bone shows an indistinct twofold division. 



Type I. 



RIGHT FEMUR OF PHRYNOSOMA DOUGLASSII. NO. L 50 12, U. S. NAT. MUS. 



Pu 3. Pig. 43. Ryn. Tab. IT 



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 lamella? with oval lacuna? 

 and long canaliculi surrounding the medullary canal. Little or no differentia- 

 tion has occurred. The section has a uniform structure. 



Type I. 



