NO. 3 COMPARATIVE HISTOLOGY OF FEMUR FOOTE 165 



RIGHT FEMUR OF A NEGRO. NO 6, MED. DEPT. TULANE UNIV. 



Pl. 25, Fig. 336. Syn. Tab. VIII 



Antero-posterior diameter of bone, 33.5 mm.; lateral, 27 mm. 



Antero-posterior diameter of medullary canal, 13 mm. ; lateral, 10 mm. 



The medullary canal is fuH. Medullary index, 17%. 



Structure. — With the exception of the posterior ridge, the section is sur- 

 rounded by a band of lamellae of varying widths, interrupted by Haversian 

 systems of the (Ta) and (C) differentiations. On both sides of the ridge the 

 lamellfe are separated into crude laminae by short concentric canals. The la- 

 mellae occupy nearly the whole of the anterior wall. The central ring is very 

 irregular and limited to the posterior and inner wall. It is composed of well 

 developed Haversian systems and inter-Haversian lamellae. 



Internal circumferential lamellae form a very irregular ring around the 

 medullary canal. In the outer wall it expands into a wide semicircular area 

 of laminae, interrupted by Haversian systems of the (la) and (C) differentia- 

 tions. 

 ■ Type I-II-III, la, C. 



RIGHT FEMUR OP A NEGRO. NO. 6.3, MED. DEPT. TULANE UNIV. 



PL. 25, Fig. 337. Syn. Tab. VIII 



Antero posterior diameter of bone, 32 mm.; lateral, 28 mm. 



Antero-posterior diameter of medullary canal, 20 mm.; lateral, 14 mm. 



The medullary canal is full. Medullary index, 45%. 



Structure. — A narrow ring of external circumferential lamellie surrounds 

 the l)one. Beginning on the outer side of the posterior ridge and extending 

 around the outer lateral and anterior wall is a wide band of lamellae, laminae, 

 and Haversian systems. After leaving the anterior wall the lamellar band is 

 displaced by Haversian systems and as the posterior wall is approached the 

 lamellar band again appears. These interrupted bands are the remains of the 

 horseshoe. Underneath the band is an incomplete central ring of well de- 

 veloped Haversian systems. 



The internal circumferential lamellae form an enclosing ring around the 

 medullary canal. It is widest in the inner wall. 



Type I-II-III, la, C. 



LEFT FEMUR OF A NEGRO. NO. 5, MED. DEPT. TULANE UNIV. 



Pl. 25, Fig. 338. Syn. Tab. VIII 



Antero-posterior diameter of bone, 25 mm.; lateral, 24 mm. 

 Antero-posterior diameter of medullary canal, 16 mm.; lateral, 15 mm. 

 The medullary canal is full. Medullary index, 67%. 



