192 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 35 



RIGHT FEMUR OF A WHITE MALE, AGE 60. NO. 145, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 31, Fig. 395. Syn. Tab. X 



Autero-posterior diameter of bone, 30 mm. ; lateral, 29 muL 



Autero-posterior diameter of medullary canal, 16 mm. ; lateral, 18 mm. 



The medullary canal is full. Medullary index, 49%. 



Structure. — The external circumferential lamelljB are fragmentary and half 

 systems occur on the external boundary of the section. The central ring is 

 composed of well developed, large and small Haversian systems. Many senile 

 changes occur in the anterior and posterior wall. Few cross canals are seen. 

 The internal circumferential lamellse form a narrow ring around the medullary 

 canal and in the anterior and posterior wall cancellous bone. 



Type III, C, senile. 



LEFT FEMUR OF A WHITE FEMALE. NO. 174, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 31, Fig. 396. Syn. Tab. X 



Antero-posterior diameter of bone, 27 mm.; lateral, 26 mm. 



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



The medullary canal is full. Medullary index, 35%. 



Structure. — The external circumferential lamella? suri-ound the section. In 

 the outer wall they form a wide background of about half the width of the 

 wall in wluch are numerous Haversian systems. The background gradually 

 disappears in the anterior wall and the lamellfE are reduced to a very narrow 

 rim. In the inner wall the narrow rim gradually widens again as it approaches 

 the posterior ridge. The central ring is composed of large and small Haversian 

 systems, many of which are senile. Near the external surface of the posterior 

 ridge groups of round and oval lacunae appear between the systems. The in- 

 ternal circumferential lamelte are fragmentary. 



Type I-III, C, senile. 



right femur OF A WHITE MALE. NO. 157, MED. DEHT. NOKTHWESTERN UNIV. 



Pl. 31. Fig. 397. Syn. T.\b. X 



Antero-posterior diameter of bone, 30 mm.; lateral, 29 mm. 



Antero-posterior diameter of medullary canal, 16.5 mm.; lateral, 16 mm. 



The medullary canal is full. Medullary index, 44%. 



Structure. — The external circiuuferential lamelhe, separated into lamina* in 

 the lateral wall, surround the section. 'I'lic central ring is composed of Ha 

 versian systems, and senile changes are ahiiiulanl. In Ihe inner wall may be 

 seen distinct remains of tlie laineilar horsesluH'. 'I'lic intei-nal circumferential 

 lamellae are fragmentary. 



Type I-II-III, C, senile. 



