200 SMITHSONIAN CONTEIBUTIONS TO KNOWLEDGE VOL. 35 



ous Haversian systems of the (lb) differentiation. The two bones are separated 

 by a narrow partition of cancellous bone (fig. 413C). Internal and external 

 circumferential lamellfe in both bones are fragmentary. 

 Type I-III, lb, C, senile. 



LEFT FEMUK OF A WHITE FEMALE. NO. 164, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 33, Fig. 414. Syn. Tab. XI 



Antero-posterior diameter of bone, 28 mm. ; lateral, 27.5 mm. 



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



The medullary canal is full. Medullary index, 55%. 



Structure. — The external circumferential lamellfe appear only in short frag- 

 ments. The central ring is composed of large and small, irregularly shaped Ha- 

 versian systems in a background of lamellae which extends around the bone. 

 The systems are generally senile. The wall of the bone is thin. The anterior 

 and inner wall is nearly half destroyed by senile losses. 



Internal circumferential lamelljE occur in frag-ments. 



Type I-III, C, senile. 



LEFT FEMUR OF A WHITE FEMALE. NO. 166, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 33, Fig. 415. Syn. Tab. XI 



Antero-posterior diameter of bone, 26.5 mm. ; lateral, 26 mm. 



Antero-posterior diameter of medullary canal, 14 mm.; lateral, 13 mm. 



The medullary canal is full. Medullary index, 34%. 



Structure. — Beginning on both sides of the posterior ridge and extending 

 around the lateral wall are two bands of lamella?, incompletelj' separated into 

 laminfe and interrupted by Haversian systems. Tlie band disappears entirely 

 in the anterior and antero-lateral wall. The external surface of the posterior 

 ridge shows many large, oval lacunas between the Haversian systems. The cen- 

 tral ring is composed of Haversian systems, large and small, with considerable 

 inter-Haversian lamellae. The systems show many senile changes. The internal 

 circumferential lamellae are fragmentary. 



Type I-III, C, senile. 



RIGHT FEMUR OF A WHITE MALE ( SUICIDE ), AGE 22. NO. 175, OR. MED. COLL. 



Pl. 33, Fig. 416. Syn. Tab. XI 



Antero-posterior diameter of bone, 27 mm. ; lateral, 29 mm. 

 Antero-posterior diameter of medullary canal, 14 mm.; lateral, 19 mm. 

 The medullary canal is full. Medullary index, 53%. 



