110 SMITHSONIAN CONTTilBUTIONS TO KNOWLEDfiE VOL. 35 



RIGHT FEMUR OF POTOS CAUDIVOLVULUS. KINKAJOU. AMER. MUS. NAT. HIST. 



Pl. 12. Fio. 318. Syx. Tab. VI 



Antero-posterior diameter of boue, 7 iiini. ; lateral, 8 mm. 



Antero-posterior diameter of inedullnrv canal, 4.5 mm.; lateral, 5.5 mm. 



Tlie medullary canal is full. Meilullary index, 80%. 



Structure. — The section lias three divisions. The external circumferential 

 lamella; form a narrow band around the anterior and lateral wall. Their lacuna; 

 are oval and their canaliculi are straight. The central ring is composed of 

 Haversian systems and iuter-IIaversiau lamellas with oval lacuna; and bushy 

 canaliculi. The ring forms the inner wall with the exception of the internal 

 lamelke. The internal circumferential lamelte form a ring around the medul- 

 lary canal. 



Type III, C. 



RIGHT FEMUR OF LUTRA CANADENSIS. OTTER. NO. 30191, AMER. MUS. NAT. HIST, 



Pl. 12, Fk). 211). Syn. Tab. VI 



Antero-posterior diameter of bone, l-t.5 mm. ; lateral, 11 mm. 



Antero-posterior diameter of medullary canal, 7 mm. ; lateral, 5 mm. 



The medullary canal is full. Medullai-y index, 28%. 



Structure. — The external circumferential lamellae appear in fragments. 

 The central ring constitutes nearly the whole section and is composed of well 

 developed Haversian systems. In the posterior wall the systems are separated 

 by lamella; with oval lacuna; and straight canaliculi. The internal circum- 

 ferential lamella> surround the medullary canal and form a wide band in the 

 outer wall. 



Type III, C. 



RIGHT FEMUR OF SIMIA SATYRUS. ORANG-UTAN. (BORNEO.) NO. 154304, 



U. S. NAT. MUS. 



Pl. 13, Fig. 220. Syx. Tab. VI 



Antero-posterior diameter of l)one, 20 mm.; lateral, 30 mm. 



Antero-posterior diameter of medullary canal, 11 mm. ; lateral, 16 mm. 



The medullary canal is full. Medullary index, 41%. 



Structure. — The exteriuil circumferential lamella' are deficient in a ])ortioii 

 of the anterior wall, the Haversian systems of the central ring reaching the sur- 

 face at this point. The lamelhi? begin to increase in thickness as they pass 

 around the inner wall where tli(\v form nearly onethiiil of its width. They 

 then diminish in thickness as they reacii the posterior wall, then slightly increase 

 in the outer wall, and linally disappear as they approach the anterior wall. In 



