SMITHSONIAN WIS " ELLANEOUS COLLECTIONS 



VOL. 72, NO. 10, PL. 1 





Fig. I. a. Cross section of the bone substance of the lower jaw of a Mas- 

 calonge, Esox, showing vascular channels. 

 I.E. Tangential section of a cranial bone of the Mascalonge, showing 

 parallel rows of small objects in the bone substance. 



2. Cross section of the lower jaw of the Mascalonge, showing the 



early differentiation of Haversian systems. 



3. Tangential section of the inner ridge of the lower jaw of Masca- 



longe, showing the circulation. 



4. Cross section of the femur of a medium sized bullfrog, Rana 



catesbeiana, showing the structure. 



5. Longitudinal section of the femur of a medium sized bullfrog, 



Rana catesbeiana, showing the looped vascular canals of the 

 inner wall. C, center of the shaft. 



6. Cross section of the femur of an alligator. Alligator mississippi- 



ensis, showing the structure. 



7. Tangential section of the same, showing the circulation. 



8. Cross section of the femur of a domestic turkey, Meleagris gallo- 



pavo, showing the structure. 



9. Tangential section of the same, showing the circulation. 



