162 SKELETON OF THE HORSE. 



in man, by the coalescence of the basioccipital with the 

 basisphenoicl ; the parts of the dura mater or outer mem- 

 brane of the brain, called "tentorium," with the posterior 

 part of the " falx," are ossified. The sella turcica is shal- 

 low, but well defined behind by the overhanging poste- 

 rior clinoid processes: the petrosal shows a deep, trans- 

 verse, cerebellar fossa, and is perforated by the carotid 

 canal. The frontal forms a small rhinencephalic fossa, 

 and contributes a very large proportion to the formation 

 of the orbital and olfactory chambers. 



In Fig. 27, 62 is the ilium, 63 the ischium, and 64 the 

 pubes, 65 is the femur or thigh-bone, 66 the tibia, 66' the 

 patella or kneepan, 67 the fibula, 68 the tarsus, and 69 

 the metatarsus and phalanges of the hind-foot ; the num- 

 bers on the other bones correspond with those in the" 

 skeleton of the dugong. 



SKELETONS OF HOOFED QUADPvUPEDS — 

 THE HORSE. 



The contrast, as regards the sphere of life and kind of 

 movement between the seal and the horse is very great; 

 the instruments of locomotion, and indeed the whole 

 frame, need to be very different in an animal that can 

 only shufile on its belly along the ground, and one that 

 can traverse the surface of the earth at the rate of four 

 miles in six minutes and a half, as was achieved by the 

 noted racer " Flying Childers." The modifications in the 

 form and proportions of the locomotive members are 

 accordingly extreme. The limbs in the horse are as 

 remarkable for their length and slenderness, as in the 

 seal for their brevity and breadth. Both fore and hind 

 limbs in the horse terminate each in a single hoof; the 



