Herrick, Nerve Components of Bony Fishes. 299 



one large one mesally of a big vessel and a minute twig 

 laterally of it. The latter {hy. j) runs down along the in- 

 ner face of the interopercular bone and at about the middle 

 of that bone divides. One ramulus pierces the bone and 

 supplies the overlying skin cephalad of this point; the 

 other ramulus continues forward in the original position 

 along the inner surface of the interopercular and finally 

 divides again, both parts piercing this bone to end in the 

 skin covering it. It can be traced forward under the eye 

 up to 400. The ramuli of this more lateral twig supply 

 practically the whole cutaneous area over the interoper- 

 cular bone. 



The more mesal branch of the r. hyoideus runs forward 

 along the dorsal limit of the branchiostegal membrane 

 under the bones of the hyoid arch. Here it breaks up to 

 supply the branchiostegal muscles {/ly. 4^ m. hyoideus of 

 Vetter) and the surfaces of the branchiostegal membrane. 

 One twig of the latter type {/iy. 5) can be followed nearly 

 to the cephalic end of the ceratohyal bone (350). 



The coarse fibres of the r. hyoideus are mainly dis- 

 tributed to the branchiostegal muscles, but some of them 

 go out to the skin with the general cutaneous branches. 

 Stannius mentions ('49, p. 62) that movement of the 

 branchiostegal membrane follows stimulation of the trun- 

 cus hyomandibularis. No cutaneous sense organs were 

 found in the areas supplied by any of the branches of the 

 r. hyoideus. The fine fibres of this nerve are derived ex- 

 clusively from the general cutaneous nerve bundle, /. e., 

 the r. communicans from the Gasserian ganglion. They 

 comprise, moreover, the whole of that component except 

 the portion already given off to the r. opercularis super- 

 ficialis. This can be demonstrated with ease, for the 

 general cutaneous component of the truncus hyomandibu- 



