NO. 3 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 



61 



RIGHT FEMUR OF AJAIA AJAJA. ROSEATE SPOONBILL. NO. 2858, AMER. MUS. NAT. HIST. 



Pl. 5, Fig. 76. Syn. Tab. Ill 



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

 Antero-posterior diameter of medullary canal, 5 mm.; lateral, 4.5 mm. 

 Medullary index, 114%. 



Structure.- — With the exception of two rather crude Haversian systems 

 in the posterior ridge the section is composed of lamellae with oval lacunae and 

 bushy canaliculi, separated by canals of a branching character into crude 

 laminae. The general direction of the canals is concentric. The bone shows 

 very little differentiation of structure. 



Type I-IL 



RIGHT FEMUR OF TYMPANUCHUS AMERICANUS. PRAIRIE CHICKEN. CR. MED. COLL. 



Pl. 5, Fig. 77. Syn. Tab. Ill 



Antero-posterior diameter of bone, 5 mm. ; lateral 6 mm. 



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



The medullary canal is empty. Medullary index, 148%. 



Structure. — The bone is composed of lamellae, crossed at all angles by short 

 canals, some of which extend inward from the external surface. In the pos- 

 terior and outer wall they unite and form a coarse network, while in the 

 anterior and inner wall they do not. Their lacunae are oval or narrow and their 

 canaliculi are bushy or long and branching. 



A very few Haversian systems of the (Ic) stage are found interrupting 

 the lamellae of the anterior and inner wall. In the posterior wall are two ridges 

 separated by a concave intermediate wall of bone. Two or three undeveloped 

 Haversian systems are found in each ridge. 



The internal circumferential lamellae surround the medullary canal. They 

 are well developed. Their lacunae are long and narrow and their canaliculi are 

 long and branching. 



Type L 



RIGHT FEMUR OF NUMIDA MELEAGRIS. GUINEA FOWL. CR. MED. COLL. 



Pl. 5, Fig. 77f Syn. Tab. Ill 



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

 Antero-posterior diameter of medullary canal, 5 mm. ; lateral, 6 mm. 

 The medullary canal is full. Medullary index, 116%. 



Structure. — The section is composed of crude laminae with oval lacunae and 

 bushy canaliculi, interrupted by Haversian systems of the (Ic) differentiation. 

 In the anterior and posterior wall the laminae have a radial direction. The 



