212 



SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



vol. 35 



Structure. — The external circumferential lamellae, separated into short la- 

 minae and interrupted by many Haversian systems, surround the section. The 

 central ring blends with the external and internal rings and is composed of 

 Haversian systems and lamellae. 



The internal circumferential lamellae, expanding into a semicircular laminar 

 area in the inner wall, surround the medullary canal. 



Type I-II-III, C. 



LEFT FEMUR OF A WHITE MALE. NO. 296, CR. MED. COLL. 



Pl. 35, Fig. 452. Syn. Tab. XI 



Antero-posterior diameter of bone, 27.5 mm. ; lateral, 23 mm. 

 Antero-posterior diameter of medullary canal, 12 mm.; lateral, 10 mm. 

 The medullary canal is full. Medullary index, 23%. 



Structure. — A horseshoe band of lamellae, frequently interrupted by com- 

 plete and crude Haversian systems of the (la) differentiation, surrounds the 

 section. It is widest in the anterior wall. The lacunae are round, oval, long, 

 and narrow. 



The central ring, irregular in shape, is composed of well developed Ha- 

 versian systems and forms the entire thickness of the posterior wall. The 

 lacunae are oval. The systems are united by many cross canals. 



Internal circumferential lamellae form a narrow ring around the medul- 

 lary canal with the exception of the posterior wall. In the anterior wall it 

 becomes cancellous. 



Type I-in, la, C. 



LEFT FEMUR OF A WHITE MALE, AGE 40. NO. 1, NEBRASKA STATE HOSPITAL 



Pl. 35, Fig. 453. Syn. Tab. XI 



Case of idiopathic epilepsy. Patient had 20 convulsions the day of his 

 death. 



Antero-posterior diameter of bone, 27 mm.; lateral, 22 mm. 

 Antero-posterior diameter of medullary canal, 24 mm. ; lateral, 18 mm. 

 Medullary index, 277%. 



General character of the bone. — The femur was small in size. With the 

 exception of a surrounding shell of bone from 1 mm. to 2 mm. thick, the entire 

 medullary portion had suffered an extensive softening and the bone structure 

 had disappeared. 



Structure. — The external circumferential lamellae were fragmentary. Quite 

 large canals penetrated the bone from the periosteum. 



