THE ANATOMY OF THE OX. 79' 



solar plexuses of both, and two lateral ones placed on the two 

 sides of the digits. There are usually five metatarsal veins, two 

 anterior deep ones which accompany the great metatarsal artery, 

 an anterior superficial one forming one root of the external 

 saphenous vein, also an internal and an external posterior vein. 

 These two last-mentioned veins pass upwards over the tarsus 

 and assist in forming the saphenous veins. In the anterior 

 limb there is a fourth or posterior digital vein, which accompanies 

 the common digital and internal metacarpal arteries. 



NERVOUS SYSTEM. 



In the giraflPe the cervical region of the spinal cord is very 

 long owing to the great length of the neck. In the porpoise 

 this part of the cord is the shortest. Tragulus has the spinal 

 cord small, the animal itself being small. The echidna, hedge- 

 hog, and some bats have the spinal cord not proportionate to 

 the weight of the body. The lateral lobes of the cerebellum are 

 small in tragulus,. and the pons also is very small. In the giraffe 

 it is large. The central lobe is asymmetrically contorted in the 

 horse, and also in the rhinoceros, and also in the giraffe. 



The corpora quadrigemina {Mesencephaloii) are relatively 

 large. This is a mark of low development. The posterior lobes 

 of the corpora quadrigemina are larger than the anterior, whereas 

 in carnivorous animals the anterior are the larger. In tragulus 

 the convolutions are simple. In larger ruminants the convolu- 

 tions are more numerous, and in the ox they are most numerous. 

 In all ungulates the convolutions pass from behind forwards 

 and inwards. The sylvian and the supra-sylvian fissures are very 

 indistinct and ill-marked. These two fissures are less neatly 

 and less clearly marked than in the case of the carnivora. The 

 sylvian and supra-sylvian fissures are most markedly developed 

 in the proboscidea and cetacea, next in ruminantia, next in car- 

 nivora. 



The olfactory region in ruminants is large. The horse, 

 having large eyes, has consequently large posterior corpora 

 quadrigemina. The optic nerve in ruminants is large, but the 

 thalami optici are not large. The retractor bulbi muscle is 

 supplied by the sixth pair of nerves. The fifth pair of cranial 

 nerves is large in ruminants, and it supplies the horns and the 

 sensitive region in connection with them. 



