NO. 3 COMPARATIVE HISTOLOGY OF FEMUR FOOTE 141 



anterior outer lateral wall the lamiiife form three-fourths of the wall. In the 

 anterior inner lateral wall the lamellae and laminae disappear altogether and 

 Haversian systems form the boundary of the medullary canal. 

 Type II-III, C. 



RIGHT FEMUR OF A BULL DOG (NOT A PUKE BLOOd). NO. 204, CR. MED. COLL. 



Pl. 19, Pig. 283. Syn. Tab. VII 



Antero-posterior diameter of bone, 13 mm.; lateral, 12 mm. 



Antero-posterior diameter of medullary canal, 7 mm. ; lateral, 6.5 mm. 



The medullary canal is full. Medullary index, 41%. 



Structure. — The section is surrounded by a wide horseshoe of crude laminae 

 intermixed with Haversian systems. The shoe is widest in the outer wall where 

 it forms half the width of the wall. In the inner wall the systems are irregular 

 and more numerous than elsewhere. The central ring is composed of Haversian 

 systems. It reaches the surface of the posterior ridge. Between the systems 

 near the posterior surface and extending along the external boundary on either 

 side of the ridge are oblique tendon insertions. The ring is narrowest in the 

 outer wall. The internal circumferential lamellae enclose the medullary canal. 

 They form a thick band along the inner and anterior walls. The thick band is 

 crossed frequently by cross canals. 



Type II-III, C. 



RIGHT FEMUR OF A COLLIE DOG (nOT A PURE BLOOd). NO. 203, CR. MED. COLL. 



Pl. 19, Fig. 284. Syn. Tab. VII 



Antero-iDosterior diameter of bone, 13.5 mm.; lateral, 13 mm. 



Antero-posterior diameter of medullary canal, 8 mm. ; lateral, 7.5 mm. 



The medullary canal is full. Medullary index, 50%. 



Structure. — The section is enclosed by a horseshoe of lamellae, interrupted 

 by small Haversian systems and partially separated by canals. The lamelhe 

 form nearly half of the width of the wall of the bone. The central ring is com- 

 posed of well developed Haversian systems which constitute the entire posterior 

 ridge with the exception of the internal lamellae. The internal circumferential 

 lamellae form a ring of varying widths surrounding tlie medullary canal. 



Type I-II-III, C. 



RIGHT FEMl'K OF A SPANIEL (nOT A PURE BLOOU). NO. 205, CR. MED. COLL. 



Pl. 19, Fig. 285. Syn. Tab. VII 



Antero-posterior diameter of bone, 13 mm.; lateral, 13.5 mm. 

 Antero-posterior diameter of medullary canal, 8.5 inuL ; lateral, 8.5 mm. 

 The medullary canal is full. Medullary index, 70%. 



