302 THE THIGH AND LEG. [chap. 



other forms have a similar rudiment of a third trochanter. 

 As a general rule the fibula is slender, and in its lower half 

 ankylosed with the tibia, but it is complete and distinct in 

 the genera Galeopithecus, Tupaia, Centetes, Ericulus, and 

 Solenodon. 



In the Chiroptera, the femur is slender and straight, 

 with trochanters of nearly equal size, and with a small 

 globular head, set on a very short neck, with its axis 

 pointing almost directly to the anterior or dorsal surfaces of 

 the bone. The fibula varies in condition. In Pteropus it is 

 extremely slender, and the upper end is atrophied, but in 

 many of the insectivorous Bats it is well developed. 



In the Rodentia the femur varies much. In the Hares 

 and Squirrels it is long and slender, with a third trochanter 

 immediately below the great trochanter. In the Beaver it is 

 broad and flat, and has a strong ridge about the middle of 

 the outer side of the shaft. In many other forms neither of 

 these accessory prominences exist, but the great trochanter 

 is usually much developed. 



In some forms, as the Beaver, the fibula is distinct, 

 strongly developed, and separated from the tibia, except at 

 the extremities, by a wide interosseous space. In others, as 

 the Hares, it is slender, and in its distal half united with the 

 tibia. The patella is generally elongated, fabellas are usually 

 developed, and there are often wedge-shaped ossifications in 

 the semilunar cartilages of the knee-joint. 



In the Ungulata, the femur is rather compressed, espe- 

 cially at the lower end. There is no distinct constriction 

 of the neck, separating the head from the rest of the bone. 

 The great trochanter is very large, and usually rises above 

 the level of the head. The small trochanter is not very 

 salient, and sometimes, as in the Rhinoceros (Fig. no), is a 

 mere rough ridge. The inner edge of the anterior part of the 



