NO. 3 COMPARATIVE HISTOLOGY OF FEMUR FOOTE 135 



LEFT FEMUR OF ERIGNATIIUH BARBATUS. SEAL. NO. 19347, AMER. MUS. NAT. HIST. 



Pl. 18, Fig. 270. Syn. Tab. VII 



Antero-posterior diameter of bone, ID.o mm. ; lateral', 39 mm. 



Antero-posterior diameter of medullary eanal, 10 mm.; lateral, "Jo mm. 



The medullary canal is full. Medullary index, 50^. 



Structure. — Three divisions are present. The external circumferential la- 

 mellje form a narrow enclosing ring. The lacuna? are oval. 



The central ring is composed of well developed Haversian systems, short 

 laminae, and lamellae with cross canals intermixed. It shows no plan of arrange- 

 ment, but a confusing mixture of units. The lacunas are oval and long and the 

 canaliculi are straight. The ring constitutes nearly all of the section. The 

 internal circumferential lamellae form an incomplete ring around the medullary 

 canal. In the lateral walls the lamellae take the cancellous form. The })lanless 

 arrangement of its three units is somewhat significant. 



Type II-III, C. 



LEFT FEMUR OP BOS BUBALIS. WATER BUFFALO. NO. 27770, AMER. MUS. NAT. HIST. 



Pl. 18. Fig. 371. .Syx. Tab. VII 



Antero-posterior diameter of bone, 48 mm.; lateral, 45 mm. 



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



The medullary canal is full. Medullary index, oS'/c. 



Structure. — Beginning on the inner side of the posterior and extending 

 around the inner, anterior, and a portion of the outer wall is a wide band of 

 laminiP, short and long, crossed by a great number of branching canals and 

 interrupted in the anterior and outer wall by a few Haversian systems. Under- 

 neath this band in the inner and anterior wall is a crescent of Havesian sys- 

 tems and lamellae with oval lacuna? and bushy canaliculi. The crescent is crossed 

 by numerous canals. The outer wall is composed of Haversian systems and 

 short laminae and the posterior wall of Haversian systems and intei'-Haversian 

 lamellffi witli oval lacuna^ and bushy canaliculi. The medullary canal is sur- 

 rounded by a narrow ring of internal circumferential lamella'. 



Type II-III, lb, C. 



left femur of ovis montana. moltntain sheep. cr. med. coll. 



Pl. is. Fig. 272. Syx. Tab. \'II 



Antero-posterior diameter of bone, 20 mm.; lateral. 2.") muL 

 Antero-posterior diameter of medullary canal, 12.. "3 imn.; lateral, 1.") muL 

 The medullary canal is full. Medullary index, 607c. 



Structure. — The bone is composed of short concentric laminae enclosing the 

 medullary canal, with the exception of the crescent of Haversian systems in 



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