140 NERVE COMPONENTS OF BONY FISHES. 



similar to the last, and finally terminates in two large 

 naked sensory papillae (o.j and 0.4). Most of the fine 

 fibres are given off with the earlier branches, but some 

 seem to persist quite to the end of the nerve. The coarse 

 fibres, including those which supply the three sense 

 organs described, as well as those which go out with the 

 other ramuli and were not traced to sense organs, are 

 somewhat smaller than the largest lateral line fibres, but 

 much larger than any communis fibres. 



The operculum is covered with large scales ; it is, there- 

 fore, difficult to get perfectly continuous series of sections 

 of the skin and my sections are imperfect in the middle 

 part of the operculum, so that, while the trunk of this 

 nerve can be followed easily, yet its fine cutaneous 

 branchlets are usually lost before they reach their final 

 distribution. 



On the opposite side of the specimen plotted branches 

 of the r. opercularis superficialis VII were traced to four 

 naked cutaneous sense organs. One corresponds to the 

 organ 0.5 of the plots, and another is somewhat behind 

 this and a little ventrally of it. Two organs were found 

 near the ventral edge of the operculum and lying some- 

 what cephalad of those figured on the plots. The second 

 may correspond to the first of the plots, or both may lie 

 in front of the latter. 



Having been led to believe from the appearance of my 

 sections that more perfect preparations would reveal a 

 larger number of cutaneous sense organs on the opercu- 

 lum, I made surface preparations of the operculum of a 

 number of specimens. The operculum of a small speci- 

 men which has been preserved in 10 per cent formalin can 

 easily be removed and examined as a transparent object, 

 particularly if the pigment-bearing mucous lining of the 

 inner surface be first stripped off. Fig. 27 is a camera 

 sketch of such a preparation examined in water without 

 staining or clearing and controlled by several similar 

 preparations, as well as others stained in various ways. 



