THE HOMOLOGIES OF THE OCCIPITAL AND 



FIRST SPINAL NERVES OF AMIA AND 



TELEOSTS. 



EDWARD PHELPS ALUS, Jr. 



In a recent and extensive work Fiirbringer (No. 2) treats 

 of those nerves of vertebrates that lie between the vagus, or 

 vago accessorius, and the first free spinal nerve. This last 

 nerve, although not definitely so defined by him, is seen, by 

 inference, to be the first nerve posterior to the last one that 

 issues from the cranio-spinal canal either through a foramen in 

 the cranium or by an aperture that lies anterior to a dorsal 

 vertebral arch segmentally related to the cranium. The nerves 

 that lie between this first free spinal one, so defined, and the 

 vagus are all included under the general term spino-occipital, 

 and are subdivided into two groups. The nerves that are 

 assigned to one of these two groups are said to have belonged, 

 with their associated skeletal elements, since an early phyloge- 

 netic period, to the occipital region of the skull, and they are 

 accordingly called the occipital nerves. Those belonging to 

 the other group are said to have acquired their relations to the 

 cranium by a more recent assimilation of their associated 

 skeletal elements, and to be as yet but incompletely emanci- 

 pated from the spinal nerves. As they thus represent an 

 intermediate stage between the nerves of the first group and 

 the free spinal ones they are called the spino-occipital nerves. 

 These three names for the nerves here under consideration 

 will be adhered to in the present article, although I think the 

 adoption of them in the present state of our knowledge of the 

 subject a needless complication, and even a possible source of 

 error or inconvenience. 



From Fiirbringer's several special descriptions of these two 

 groups of nerves, and his several general statements regarding 

 them and their associated skeletal elements, it is seen that he 

 considers as occipital nerves all those that issue from the 



