NO. 3 COMPARATIVE HISTOLOUV OF FEMUR FOOTE 119 



EIGHT FEMITK OF THYLACINUS CYNOCEPHALUS. TASMAXIAN WOLF 



Pl. 14. Fig. 237. Syn. Tab. VI 



« 



Antero-posteriov diameter of bone, 19.5 mm.; lateral, 15 mm. 



Antero-posterior diameter of medullary eanal, 8 mm. ; lateral, 8.5 mm. 



The medullary canal is full. Medullary index, 28%. 



Struct lire. — The section is surrounded by a nari-ow rins' of external lamellae, 

 interrupted here and there by crude Haversian systems of the (la) differen- 

 tiation. Underueatli this ring- is a wide horseshoe of lamellae, interrupted by 

 many crude Haversian sysfems of the (Ta) differentiation arranged concen- 

 trically. The outer wall is all lamellae. 



Underneath this l>and is a central, incomplete ring of well developed Ha- 

 versian systems witli inter-Haversian lamellae. In the posterior wall the sys- 

 terns form nearly the whole of the wall. Here the oval large lacima? with 

 bushy canaliculi are pronounced. 



Internal circumferential lamellae form a nai-row ring around the medullary 

 canal. Their lacunae are long. 



Type I-III, la, C. 



RIGHT FEMUR OF DASYPROCTA AGOUTI. NO. 15669, AMER. MUS. NAT. HIST. 



Pl. J 4, Fig. 238. Syn. Tab. VI 



Antero-posterior diameter of bone, 10 mm.; lateral, 8 mm. 



Antero-posterior diameter of medullary canal, 6.5 mm. ; lateral. 5 mm. 



The medullary canal is full. Medullary index, 93%. 



Structure. — The three divisions are well marked. A wide ring of external 

 circumferential lamelLT, iiitcnupted by crude Haversian systems of the (la) 

 differentiation and crossed by canals, surrounds the section with the exception 

 of the posterior ridge. The lamellar ring forms more than half of the section. 

 The central ring is comijosed of well developed Haversian systems with inter- 

 Haversian lamelltt. 



The systems of the central ring reach the surface al the jiosterior ridge 

 where they are separated by bone substance with oval lacnnje. The internal 

 circumferential lamellae form a narrow ring around tlie modullaiy canal. The 

 lacunae are long in the external and internal lamelhe; elsewheic tliey are oval. 



Type I-III, la, C. 



LEFT FEMUR OF LASIOPYGA CENTR.ALIS JOHNSTONI. .4FKICAN MONKEY. NO. 27705, 



AMER. MUS. N.4T. HIST. 



Pl. 14, Fig. 239. Syn. Tab. VI 



Antero-posterior diameter of bone, 9 mm. ; lateral, 8 mm. 

 Antero-posterior diameter of medullary canal, 5.5 mm. ; lateral, 5 mm. 



9 



