288 



AN INTRODUCTION TO ZOOLOGY 



lies a large sesamoid bone, the patella or knee-cap, and behind it are 

 another series of small bones, the fabellse. 



The tibia and fibula are two long 

 bones, the former much larger than 

 the latter, which are free proximally 

 but fused distally. The tibia is a 

 long stout bone with an enlarged 

 proximal extremity for articulation 

 with the femur and bearing on its 

 anterior surface a prominent cnemial 

 crest, while its distal end articulates 

 with the talus. The fibula is a 

 slender bone, free proximally but 

 fusing distally with the tibia and 

 also bearing a facet for articulation 

 with the calcaneum. The tarsalia in 

 Lepus have been reduced to six 

 bones. The proximal row consists 

 of two bones, of which the inner 

 represents the tibiale and inter- 

 medium fused and is often termed 

 the talus, while the outer or fibulare 

 is termed the calcaneum. The 

 centrale or navicular is a bone con- 

 tinuing the line of the talus and 

 sending forward a slender process 

 on the under surface of the foot. 

 There are but three distal carpalia, 

 the first or ento-cuneiform is alto- 

 gether lacking as a separate element, 

 but is probably fused with the second 

 metatarsal so that the innermost is 

 really the second or meso-cuneif orm ; 

 the next is the third ecto-cuneiform 

 and the remaining bone represents 

 two tarsalia fused, and is termed the 

 cuboid. Only four metatarsals are 

 present, the first, corresponding with 

 the metatarsal of our big toe, is 

 absent, as indeed is the whole toe. 

 The remainder are long bones, the innermost bearing a back- 

 wardly projecting 'corner which, as has just been pointed out, is 

 probably the innermost distal tarsal. Each metatarsal is followed 

 by a digit composed of three phalanges. 



FIG. 95 Left hind foot of Lepus, 

 viewed from extensor surface. 



C., centrale, navicular ; Cu., cuboid ; 

 EC., ecto-cuneiform ; En., process prob- 

 ably representing ento-cuneiform ; F., 

 fibiale, calcaneum ; M., meso-cuneiform ; 

 Me., metatarsal ; P., phalanx ; T., talus 

 tibiale + intermedium ; Un., ungual pha- 

 lanx ; II.-V., digits. 



