Cjiap. VIII.] AND OF AMPHIBIA. 121 



( 



Auditory. 



^'^ »» ■ Facial; supplying the superficial muscles of the 

 face, &c. 

 fGlosso-'pharyngeal (gustatory nerve and nerve of 



common sensibility for the pharynx). 

 Vagus, or Pneumo gastric (sensory nerve of respi- 

 8th „ ^ ratory organs, heart, alimentary canal, liver, 



kidneys, &c. 

 8_pinal accessory; supplying the muscles of the 

 larynx, &c. 



9th , Sublingual, or Hypoglossal ; motor nerve of tongue 

 and of muscles which move it. 



From this table it will be seen that three of the ' pairs ' 

 of cranial nerves (5th, 7th, and 8th) are compound in their 

 nature. Their parts have, moreover, little in common, 

 except for the fact that the components of each so-called 

 * pair ' in man and many of the lower animals pass side by 

 side through the same hole in the skull. This, indeed, 

 seems to have been the principal reason actuating the 

 earlier anatomists when they grouped them together.* 

 No cranial nerves answering to the 9th pair exist in 

 Fishes : their functions being discharged by branches 

 from the first spinal nerve. The motor root of the 8th, 

 the ' spinal accessory,' is also less distinct as a separate 

 nerve in Fishes and some Eeptiles, than it is in higher 

 vertebrates. 



Looked at from the point of view of the functions which 



* Except in the case of the two divisions of the 5th nerve, this 

 grouping was not respected in the classification of Soemmering 

 (1778). According to him, the cranial nerves were to be regarded as 

 twelve pairs, the first six agreeing with those of WilHs, whilst the 

 facial is called the 7th, the auditory the 8th, the glosso-pharyngeal 

 the 9th, the vagus the 10th, the spinal accessory the 11th, and the 

 sublingual the 12th. 



