Herrick, Nerves of Stluroid Fishes. 215 
supplied by nerves of the acustico-lateralis system and the latter 
by nerves of the communis system in all cases where the inner- 
vation can be determined with accuracy ; and now it remains to 
inquire regarding the structure and arrangements of the organs 
themselves. 
I. ORGANS OF THE COMMUNIS SYSTEM. 
Here, as in other teleosts, the terminal buds of the outer 
skin and the taste buds of the mouth are not only similar in 
their innervation (communis nerves in both cases) but they are 
essentially similar in structure. 
Fig. 11 illustrates a typical terminal bud from the skin of 
the top of the head. The skin has the typical structure so 
accurately described by Wricut (84, p. 251, seq.), and the 
sense bud is seen to consist of a simple epithelium of enor- 
mously elongated cells. They are, however, hardly long enough 
to reach all of the way through the thick epidermis ; accord- 
ingly the dermis is raised under the organ into a papilla upon 
the apex of which the sensory epithelium rests. The nerve 
pierces the dermis under the center of the organ and is com- 
posed of larger fibers than those ordinarily found in the com- 
munis system, with very densely staining medullary sheaths. 
This peculiarity of the nerve fibers is the only important differ- 
ence which I have been able to discover between the terminal 
buds of the outer skin and the taste buds of the pharyngeal 
cavity. In both cases, when it is possible to trace the nerves 
back to their origin with precision, they are found to arise from 
communis roots of the VII, IX or X cranial nerves. In both 
cases the organs are strictly superficial and usually the apex lies 
in a papilla slightly elevated above the surrounding surface of 
the epithelium. 
II. ORGANS OF THE ACUSTICO-LATERALIS SYSTEM. 
Besides the organs of the internal ear, which are not con- 
sidered in this contribution, there are three types of sense 
organs belonging to the acustico-lateralis system in Ameiurus, all 
lying in the skin or immediately beneath it. Following the 
