Anatomy of Fibula. 363 



Hare {Lepus eurflpaeus). 



Tliis animal, with his long foot at a right angle like the 

 Kangaroo, and able also to sit up, shows an even more advanced 

 type of disappearance of the Fibula than seen in that marsupial. 

 Only the upper third remains. No trace of the lower half can 

 be distinguished. The lower end of the fragment is fused to 

 the Tibial shaft, and the upper extremity is fused to the outer 

 Tuberosity of the Tibia. 



Sheep (Bovidak). 



The Fibula as such has disappeared. There are no evidences of 

 it above, except a well marked fibrous band extending from 

 the External Tuberosity of the Tibia to just above the middle 

 of the shaft of that bone. On the lower, articular face of the 

 Tibia a groove is seen representing the former separation of 

 the Fibula. 



Deer (Ckrvidae). 



Here the Fibula has disappeared, the only trace being a 

 bony spicule about three-quarters of an inch long, depending 

 from the outer Tuberosity of the Tibia. 



Mongoose {Herpcstes). 



Here we have lono; feet frlvino- a ";ood base to allow for 

 springing. The Fibula is thin and slender especially in the 

 uj^iier third. There is an ill-defined articulation above with 

 the outer Tuberosity of the Tibia. The lower end does not 

 partake in the formation of the ankle-joint acting merely as 

 an outside support to the articulation. 



Hopse {Equus). 



The Fibula is represented by a spicule of bone abutting down 

 from the Outer Tibial Tuberosity. The Koala does not depend 

 on the peloic limb for propulsion speed nor for continuous 

 support. Where high speed continued over long peilods is 

 necessary, as in the horse, a brme like the Fibula would un- 

 doul)tedlv weaken the Tarsal articulation. 



