SCOPE AND METHODS. 19 



terminate mainly in the tuberciilum acusticum of the 

 medulla oblongata. 



(4). The somatic motor fibres are commonly regarded as 

 represented by the eye-muscle nerves, the III, IV and VI 

 pairs, and in higher forms by the hypoglossus nerve. In 

 the fishes the latter is a true spinal nerve. 



(5). The viscero-motor fibres comprise the motor roots of 

 the V, VII, IX and X nerves. 



No cranial nerve contains all of these components and 

 it is not necessary to assume that any one ever did contain 

 all of them, for some of these components are evidently 

 neomorphs in the head. Their relations and probable 

 morphological significance are discussed in Sections 3 and 

 12. This brief outline, together with the accompanying 

 text-figure and figures 3 to 5 and 8 to 1 2 will perhaps aid 

 in rendering the descriptions which follow more intelli- 

 gible. Somewhat fuller general accounts have been 

 given in my preliminary papers ('97 and '98a). 



III. — Scope and Methods. 



This investigation was begun as occupant of the 

 Columbia University Room at the Marine Biological 

 Laboratory at Woods Hole, Mass., in the summer of 1896, 

 was continued during the winter of 1896-7 in the Zoologi- 

 cal Laboratory of Columbia University, and subsequently 

 at the Pathological Institute of the New York State 

 Hospitals and at the laboratory of the U. S. Fish Com- 

 mission at Woods Hole. To all of these institutions I 

 am under obligation, not only for the facilities of re- 

 search, but for numerous special courtesies; and particu- 

 larly to Dr. Strong of the Columbia Laboratory for 

 suggestion and advice throughout. 



