PERISSODACTYLA. 701 



Giraffidse, represented solely by the giraffe (Giraffa camelopardalis), 

 a tall Ethiopian animal, notable for its enormously elongated 

 cervical vertebrae, and for its long limbs. It is gregarious in its 

 habits, and feeds on the leaves of trees. The lateral digits are 



entirely absent. The dental formula is 223. On both sexes 



3133 

 there are on the forehead short erect prominences, over the 

 union of parietals and frontals, which arise from two distinct 

 centres of ossification, but afterwards fuse with the skull. In 

 front of these there is a median protuberance. 



Antilocapridae, represented solely by the prongbuck {Antilocapra 

 americana), a North American animal, with most of the char- 

 acteristics of Bovidfe. The horny sheath bears one branch, and 

 is periodically detached from the bony core. 



Bovidse, the hollow-horned Ruminants, widely distributed throughout 

 the world, but without indigenous representatives in Australia, 

 South or Central America. The second and fifth digits may be 

 completely absent, but are often represented by minute hoofs and 

 supporting nodules of bone. The frontal appendages, if present, 

 consist of a solid bony core growing from the frontal, and a much 

 longer sheath of horn, which grows at the base as it is worn away 

 at the tip. They are not deciduous, and are usually present in 

 both sexes, though larger in the males. 

 Examples. — Antelope, Gazetta, Capra, Ovis, Bos. 



Sub-Order Perissodactyla. 

 Horses, Tapirs, Rhinoceros, and their extinct Allies. 



The middle or third digit of fore- and hind-feet is larger 

 than the others, and symmetrical on itself. It may be the 

 only complete digit, as in the horse, or it may be accom- 

 panied by a second and a fourth, and in the fore-foot of 

 tapirs and some extinct forms, by a fifth digit. No modern 

 forms have any trace of a first digit. The astragalus 

 has a pulley-like surface above for articulation with the 

 tibia; its distal surface is flattened and unites to a much 

 greater extent with the navicular than with the cuboid. 

 The last-named bone is of less importance than in the 

 Artiodactyla. The calcaneum does not articulate with 

 the lower or distal extremity of the fibula. The femur 

 has a third trochanter or process for the insertion of 

 muscles. There are usually twenty-three dorso-lumbar 

 vertebrae. 



As to the dentition, the premolars and molars form a 

 continuous series, with broad transversely ridged crowns, 

 the last premolars often very like the molars. 



