162 Edward Phelps Allis jr., 



or more stages intermediate between pit organs and terminal bnds. 

 As, however, I have not yet been able to trace the nerves that inner- 

 vate any of them to their centres of origin in the brain, it is im- 

 possible to tell definitely to which category, lateral sensory, or com- 

 munis, any of them belong. Two lines of these organs, on each side 

 of the snout of Conger, have already been referred to. One of them 

 encircles the ventral margin of the nasal tube, and is quite certainly 

 a lateral sensory line forming part of the ethmoidal commissure of the 

 fish; the other extends vertico-longitudinally along the edge of the 

 latero-rostral dermal fold, and may perhaps belong to the communis 

 system. The nerves that innervate these two lines of organs could 

 not be traced either in my sections or in dissections. • The nerves 

 that innervate the other lines could, with two exceptions, be traced, 

 in dissections, from the organs they innervate to the points where they 

 either join one of the main nerve trunks, or enter, independently, 

 canals in the bones of the skull. Farther than that I have not as 

 yet attempted to trace them, my work so far thus only showing to 

 which one of the several cranial nerves the nerve-fibres innervating 

 the several lines belong. 



Two of the lines of larger organs are found on the top of the 

 head, and seem to represent the anterior and middle lines of pit- 

 organs of Amia. The nerve that innervates the anterior line issues 

 from the skull by a small foramen that lies on the top of the skull 

 in the suturai line between the frontal and parietal bones. It runs 

 backward a short distance on the roof of the skull, then turns sharply 

 mesially till it reaches the mid-dorsal line, and there turns upward 

 around the mesial edge of the adductor mandibulae muscle and then 

 laterally along the dorsal surface of that muscle. There it soon separates 

 into two main branches, one running forward and the other backward, 

 and sends branch f^i to the several organs of the line. The peculiar course 

 of this nerve is evidently due to its having been pushed out of its 

 primary position by the adductor mandibulae muscle, as that muscle 

 gradually encroached upon the dorsal surface of the skull. 



The line that apparently represents the middle head-line is inner- 

 vated by two nerves that issue separately by two foramina on the 



