104 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 35 



developed for the most part, separated by bone substance with oval lacunaj 

 and bushy canalieuli, aud surrounded by a coarse network of canals. Their 

 lacunte are long and narrow, generally. A few, however, show round or oval 

 lacuua> with short, bushy canalieuli. The bone is uniform. 

 Type II-III, C. 



FEMUR OF SUS. DOMESTIC PIG. CR. MED. COLL. 



Pl. 11, Fig. 203. Syn. Tab. V 



Antero-posterior diameter of bone, 21.5 mm. ; lateral, 18.5 mm. 



Antero-posterior diameter of medullary canal, 16.5 mm. ; lateral, 12.5 mm. 



The medullary canal is full. Medullary index, 108%. 



Structure. — The bone, with the exception of the posterior wall, is composed 

 of concentric laminje. The laminfe are separated and crossed by wide canals 

 which frequently communicate with each otlier. The separating canals, here 

 and there, widen into circular areas which are surrounded by incompletely 

 de\'eloped concentric lamella; and form aberrant Haversian systems. The lami- 

 niP are long or short and strongly developed. They have long, narrow lacunae 

 and branching canalieuli. In the posterior wall are two areas of well develoj^ed 

 Haversian systems separated by an intermediate wall of laminae. These are 

 the only regular systems of the section. 



The femur of the adult pig is second type witli two areas of Havei'sian 

 systems in the posterior wall. Tliis bone, therefore, is essentially second in 

 tyjje as it emerges from the fetal stage, and, for the most part, remains second 

 in the adult. 



Type II-III, C. 



RIGHT FEMUR OF SUS SCROFA. WUJ) BOAR. (ARKANSAS.) CR. MED. COLL. 



Pl. 11, Fig. 201. Syn. Tab. V 



Antero-posterior diameter of bone, 23 mm.; lateral, 20 nun. 



Antero-posterior diameter of medullary canal, 15 mm.; lateral, K! nnn. 



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



Structure. — The bone is comjiosed of concentric laminae crossed and divided 

 into short segments by canals. The laminae are composed of lamella' with long 

 narrow lacunae and straight canalieuli. 



In the posterior wall are two ridges separated by the intervening portion 

 of the posterior wall. These ridges are composed of well developed Haversian 

 systems which occupy the whole tliickness of the wall from the external laminae 

 to the internal. Between the ridges the posterior wall is composed of laminae 

 alternating with Haversian systems in concentric rows. About the middle of 

 the lateral walls on both sides of the two ridges, crude Haversian systems are 



