198 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 35 



the lamellar and Haversian system band is a central ring of regular Haversian 

 systems, well developed. 



The internal circumferential lamellae form a wide baud in the lateral and 

 posterior wall. In the posterior, outer lateral wall several laminte extend 

 obliquely from the interior of the wall to the medullary surface. The external 

 lialf of the posterior ridge is composed of Haversian systems, between which 

 is bone substance with many oval lacuufe, while the medullary half is composed 

 of Haversian systems with a little inter-Haversian lamellfe. 



Type I-II-III, la, C, senile. 



LEFT FEMUR OF A WHITE MALE. NO. 100, CR. MED. COLL. 



Pl. 32, Fig. 410. Syn. Tab. X 



Antero-posterior diameter of bone, 24 mm. ; lateral, 31 mm. 



Antero-posterior diameter of medullary canal, 17.5 mm. ; lateral, 13.5 mm. 



The medullary canal is full. Medullary index, 4G%. 



Structure. — The external circumferential lamellae foi-m the boundary of a 

 part of the outer wall. In some places, however. Haversian systems form the 

 external boundary. In the outer wall laminae separate the Haversian systems 

 of the central ring. Their lacume are well developed. 



The central ring constitutes the greater jjart of the section, and especially 

 is this true of the outer wall. 



In the inner wall is a wide external band of laminae and oblong Haversian 

 systems extending from the posterior ridge around to the outer antero-lateral 

 junction. In the anterior wall is a wide band of lamelhr. The systems are large, 

 small, and irregular in shape. In tliosc ai-ouinl tlic medullary canal, senile 

 changes appear. The internal circumferential hiinclhr form an extremely nar- 

 row ring around tlie medullary canal. 



Type I-II-III, C, senile. 



RIGHT FEMUH OF A WHITE FEM.\LE. NO. 150, MED. DEFT. NORTHWESTERN UNIV. 



Vh. 32, Fig. 411. Syn. Tab. X 



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



Antero-posterior diameter of medullary canal, 20 mm. ; lateral, 21 mm. 



The medullary canal is full. Medullary index, 16%. 



Structure. — The section is irregular in shape and is composed of a back- 

 ground of lamellae, in which are irregularly shajied Haversian systems with 

 senile changes. 



Type I-III, C, senile. 



