176 Journal of Comparative Neurology. 



The main object of the study has been, as suggested 

 above, the analysis of each of the cranial nerves, especially 

 the sensory portion, into its components and the tracing 

 of these components continuously from their nuclei in the 

 central nervous system to their ultimate peripheral dis- 

 tributions. As this has necessitated the careful micro- 

 scopical study of the entire courses of these nerves, it has 

 seemed best to examine and plot the entire peripheral 

 nervous system, even those nerves which, like the pure 

 motor branches, do not bear directly upon this major 

 problem. The following pages, therefore, aim to give a 

 measurably complete account of the cranial and first 

 spinal nerves of the type chosen for the detailed analysis. 

 This mode of treatment receives further justification 

 from the fact that the nervous system of no member 

 of the family represented by this type has ever been 

 described, even topographically, so far as my knowledge 

 goes. 



The descriptive details thus accumulated, together with 

 bibliographical and critical comments upon them, so far 

 as they may be of value to special students of compara- 

 tive anatomy, are given with considerable fulness. A 

 summary at the close of each section and an analytical 

 table of contents will assist the general reader who may 

 not be interested in such details. 



The reconstructions plotted upon Figures 3, 4, 5 and 7, 

 all illustrations of cross sections of Menidia, and the dia- 

 grammatic cross sections. Figures 8 to 12, are all based 

 upon a single series of sections, and the descriptions in 

 the text have, for the most part, been written from this 

 same series. Thus individual variations do not enter into 

 the descriptions. Other specimens prepared by the same 

 and by different methods have, however, been used 



