Chap, VIII.] THE SKELETON. 175 



the opposite side of the bone to the lesser trochanter. At 

 the distal end of the bone there is an internal and external 

 condyle (the former on the same side as the head), separated 

 by the inter-condylar notch, on the pre-axial side of which 

 the small patella of the knee-cap fits. The tibia is a large 

 strong bone, with which the small fibula fuses distally on the 

 outer side. The tarsus (Fig. 57, B.) consists of six bones: a 

 large calcaneum or fibulare (fi.\ and a smaller astragalus or tibiale 

 (ti.)j in which the inter-medium is also probably merged; a cen- 

 trale, or navicular (ce.), a bone (the cuboid) on the fibular side, 

 which represents tarsale iv. and v. coalesced, tarsale iii., known as 

 the ecto-cuneiform, and tarsale ii. or meso-cuneiform. Tarsale i. 

 (ento-cuneiform) may be represented by a small process of meta- 

 tarsale ii. The homologies of the tarsus are, however, being 

 re-investigated. There are only four metatarsals, i. being sup- 

 pressed ; and four digits, the hallux (great toe) being absent. 



In the fowl the femur is a stout somewhat curved bone with a 

 strong great trochanter. In front of its distal end is a small 

 patellar nodule. On the femur follows a compound bone known 

 as the tibio-tarsus, the distal end of which (Fig. 57, C.) represents 

 one or more of the proximal row of tarsal bones. The fibula 

 (Fi) forms a thin bone lying as a splint on the tibio-tarsus, but 

 with an expanded head. Upon the tibio-tarsus follows another 

 compound bone, the tarso-metatarsus. Its proximal end represents 

 the distal row of tarsal bones which becomes fused on to the ends 

 of metatarsalia ii., iii., iv., ankylosed side by side into a single 

 bone. The first metatarsal is found at the distal end of the 

 tarso-metatarsus united to it only by ligament. The fifth meta- 

 tarsal is absent. There are four digits, of which three are 

 directed forwards, and rest with their whole ventral surface on 

 the ground. The other digit, the hallux, is directed backwards, 

 and raised off the ground at the proximal end. The fifth digit is 

 suppressed. 



Thus in the fowl the heel-joint is not, as in the rabbit, 

 between the tibia and the tarsus, but between the proximal and 

 distal portions of the tarsus, which are respectively ankylosed 

 with the tibia and the fused metatarsus. It is therefore a meso- 



