NO. 3 COMPARATIVE HISTOLOGY OF FEMUB FOOTE 137 



LEFT FEMUR OF GAZELLA GRANTL GRANT 's GAZELLE. NO. 27762, AMEH. MI'S. NAT. HIST. 



Tl. 18, Fig. 375. Syn. Tab. VII 



Anteroposterior diameter of bone, 19 mm.; lateral, 19.5 mm. 



Antero-posterior diameter of medullary canal, 10.5 mm.; lateral, II mm. 



The medullary oanal is full. Medullary index, 45%. 



Structure. — The section is composed of a wide horseshoe hand of laminae 

 embracing the posterior ridge. In the anterior wall they are interrupted by 

 Haversian systems, especially near the circumference. They are long and short 

 and their lacunae are round and oval with bushy and straight canaliculi. Under- 

 neath the lamina of the outer lateral, the anterior, and inner lateral wall is a 

 crescent of Haversian systems well developed. The posterior ridge is com- 

 posed mostly of Haversian systems. Internal circumferential lamella; with 

 narrow lacunar and straight canaliculi surround the medullary canal. 



Type II-III, C. 



LEFT FEMUR OF KOBUS ELLIPSIPRYMNOS. WATER BUCK. NO. 27669, 



AMER. MUS. NAT. HIST. 



Pl. is. Fig. 2r0. Syx. Tah. VII 



Antero-posterior diameter of bone, 28 mm. ; lateral, 25 mm. 



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



The medullary canal is full. Medullary index, 70%. 



Structure. — Beginning on the outer side of the posterior ridge and extend- 

 ing around the outer and anterior wall is an external band of lamella?, inter- 

 rujited by Haversian systems of the (la) differentiation and by canals. Their 

 lacuiRP are long and their canaliculi are straight. The inner wall of the section 

 is com])ose(l of lamina? whicii are continued around the section \n llie posterior 

 ridge under the lamellar band of the anterior and outer wall. 'J'hc laminae are 

 frequently interrupted by Haversian systems. Their lacunje are long and their 

 canaliculi are straight. The posterior ridge is composed of Haversian systems 

 which are extended around the outer and anterior wall and border uijon the 

 medullary canal. Their lacunae are long. 



Type I-II-III, la, C. 



RIGHT FEMUR OF ARCTOMYS MONAX. WOODCHUCK OR GROUND HOG. CR. MED. COLL. 



Pl. 19, Pig. 377. Syn. Tab. VII 



Antero-posterior diameter of bone, 6 mm. ; lateral, 7 mm. 



Antero-posterior diameter of medullary canal, 4 mm.; lateral, 4.5 mm. 



The medullary canal is full. Medullary index, 74%. 



Structure. — Two laminae with long lacunae and straight canaliculi, inter- 

 niiited here and there by Haversian systems of the (la) differentiation, sur- 

 round the section with the exception of the posterior ridge. 



