240 SUMMARY. 



number of dorsal nerves is seldom fewer, but often greater, than in man. In birds it 

 is generally fewer, as well as in amphibia; but in snakes and fishes a distinction 

 cannot be made. Each nerve varies according to the extent of parts supplied. The 

 lumbar, sacral, and caudal nerves of mammalia, are similar to those in man, the 

 number of lumbar is generally greater, that of sacral less ; from some of these a 

 plexus is formed, which sends off the anterior crural, obturator, sciatic, and several 

 smaller nerves. Similar nerves are given off in birds and amphibia, but vary to suit 

 the difference in the form and size of the muscles, and the required sensibility of the 

 integuments. In mammalia, the tail is supplied by an anterior and posterior caudal 

 nerve on each side ; in birds, amphibia, and fishes, by numerous small nerves issuing 

 from the spinal cord to' the end of the tail. 



The sympathetic nerve is distinct in the four superior classes ; it varies in 

 having a more or less close or open texture. In mammalia, there is a superior 

 cervical ganglion, it is very small in birds, very distinct in the snake, but not in the 

 turtle and fishes ; in man, it sends branches to communicate with the sixth, the Vidian 

 nerve, and the Gasserian ganglion ; in the monkey, it is the same, but in mammalia 

 generally there is some variation ; in birds and amphibia it communicates with the 

 ninth, the par vagum, the glosso-pharyngeal, the hard portion and fifth ; two of the 

 branches passing upwards may be compared with the Vidian ; in fishes there is a com- 

 munication with the par vagum and fifth, and as cervical ganglia do not exist, the first 

 may be compared with the thoracic sending off the splanchnic nerves. In mammalia 

 it communicates with the nerves of the pharynx, and supplies the branches of the 

 external carotid, and the salivary glands ; it also usually communicates with the glosso- 

 pharyngeal, par vagum, ninth, sometimes with the accessory, suboccipital, and one 

 or two of the superior cervical nerves. The prolongation descends to the first thoracic 

 ganglion, sometimes becoming connected in its course with one or more ganglia in 

 the neck ; it is either separate from, or adhering to, the par vagum ; in birds there is 

 a very slender branch sent with the carotid artery ; in the pelican, that of each side 

 becomes joined, and then accompanies the united trunks of the carotid, and divides 

 again to communicate with the ganglion of the last cervical nerve but one of each 



