144 



THE BONES. 



Fig. 97. 



Differential Characters in the Leg-bones of the other Animals. 



In the leg-bones there is observed, in the various domesticated iinin)als, differences analo- 

 gous to those mentioned as existing in the forearm of the pectoral limb. More particularly 

 is this the case with regard to the development of the^^twZa. Tlie relations existing between 

 the development of that bone and the number of digits, is less mark( d than tliat which exists 

 between the development of the ulna and the division of the digital region. Thus, in Rumi- 

 nants the fibula is only represented by its inferior nucleus of ossification, although there are 

 two apparent and free digits. In these animals the patella is also very narrow ; and in hU the 



domesticated species except Solipeds, the articular 

 grooves in the lower end of the tibia are directed im- 

 mediately from before to behind. 



A. Ox, Sheep, Goat.— In the Ox, the tibia is 

 short ; it is longer in the Goat and the Sheep. The 

 tibia of these animals is remarkable for : 1. The absence 

 of the lateral facet on the supero-external tuberosity. 

 2. The absence of a vertical fossa on the anterior tuber- 

 osity. 3. The absence of roughened lines on the pos- 

 terior face. 4. The obliquity downwards and inwards 

 of the inferior articular surface. The most salient point 

 of this surface is the anterior extremity of the middle 

 tenon. 



The body of the fibula and its upper extremity 

 are replaced by a fibrous cord, which is sometimes 

 ossified wliolly or in part, and may then resemble the 

 fibula of Solijieds. The inferior extremity forms a 

 small isolated bone (the tarsal coronoid bone of some 

 authorities), articulating in one direction with the tibia, 

 and in another with the calcis and astragalus. 



B. Camel. — The tibia of the Camel is very long, 

 slightly bent outwards at its upper end, and inwards 

 at the lower end. The tibial crest is high and sharp. 

 The posterior face shows only one roughened line 

 limiting the popliteal surface. 



C. Pig.— In the Pig,tlie fibula is flattened on both 

 sides, extends the whole length of the leg, and is united 

 to the tibia by its two extremities: above, by a diar- 

 throdial facet ; below, by an inteross^eous ligament. 

 It is developed from three ossifying centres; the in- 

 ferior articulates with the calcis and astragalus. 



D. Dog, Cat. — In Carnivora, the tibia, is long and 

 slender, and presents a salient anterior crest. The 

 fibula is also as long as the tibia, and is united to 

 that bone at three points : at the two extremities by 

 articular surfaces, in the inferior third and middle by 

 an interosseous ligament. 



E. Rabbit. The leg-bones of this animal much 

 resemble those of Carnivora, differing only in: 1. More 

 pronounced flattening of the tibia on each side at its 



upper end, and before and behind inferiorly. 2. The slightly salient malleoli. 3. The fibula, 

 which is fused with tlie tibia in its lower third. 



LEG-BONES OF THE RABBIT AND CAT. 



A, Boues of the Rabbit. B, Bones of 

 the Cat. 1, Diaphysis of the tibia ; 

 2, crest of the tibia ; 3, internal 

 malleolus or tuberosity of the in- 

 ferior extremity of the tibia ; 4, 

 anteiior extremity of the median 

 tenon on the inferior articular sur- 

 face of the tibia ; 5, fibula ; 6, ex- 

 ternal malleolus or tuberosity. 



Posterior Foot. 



This region, which bears the greatest resemblance to the same region in the 

 anterior limb, comprises three subdivisions — the tarsus, the metatarsus, and the 

 digital region. 



1. Bones of the Tarsus (Figs. 98, 99). 

 These are short, very compact bones, six or seven in number, and situated 



