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THE AMERICAN NATURALIST [Vol. XL 



tion in which the leg is drawn. This distal enlargement of the 

 femur is slightly convex on its anterior surface, and concave on 

 its posterior surface. On the convex anterior surface is a very 

 slight ridge, which is prolonged distally as an inconspicuous knob. 

 Almost the entire distal end of the femur articulates with the tibia, 

 but there is a small articular surface for the proximal end of the 

 fibula. Between the distal end of the femur and the proximal 

 ends of the tibia and fibula is a layer of cartilage of considerable 

 thickness. 



The lower leg is made up of two entirely distinct bones, the 

 tibia and fibula. Of these bones, the tibia (Fig. 11, T.) is larger 

 and will be described first. It is considerably larger at its proximal 

 than at its distal end, and forms almost the entire articular surface 

 of the knee-joint. The proximal end is broadened and flattened 

 in the same planes as is the distal end of the femur, with which it 

 articulates. On the anterior surface of this end is a slight ridge, 

 corresponding to the ridge that has been noted on the distal end 

 of the femur. The shaft of the tibia tapers rapidly from the 

 proximal end to a point a little beyond the middle of the bone, 

 and then increases in size to form the somewhat flattened distal 

 enlargement, which articulates with the tibiale and centrale of 

 the foot. The ihitteiiing of the distal eiid is in thi- same plane as 

 that of the more enlarocd pn.ximal end. The <listal, like the 

 proximal end, is j)n)vi(le(l with a well developed plate of cartilage. 



shown sliji'htly exaggerated in the figure, is strongly bowed on the 

 tibial side. The side away from the tibia is only slightly bent, 

 so that the bow is chiefly due to the shape of the surface next to 

 the tibia. The enlargement at the ])roxinial end is rounded, and 

 articulates laterally with the side of the tibia and })r<)ximally with 

 the distal end of the femur, ^^he shaft of the bone is somewhat 

 flattened, so that it is elliptical instead of circnlar in cross section. 

 The distal end is more enlarged flian the proxinial. bnt is flattened 

 instead of being ronn.led. At the extrein(> end of each flattened 



The fibnla. like most of the oth'er hone, rliat have been .leseribed, 

 ends, both proxi.nally and distally, in eartilage. 



The tarsus, like that of the Japanese species, is composetl of 



