EDWARD PHELPS ALLIS. 
842 
between the corresponding linear aponeuroses, while in the 
ventral portions of the muscles, where there are no apo- 
neuroses to interrupt the muscle fibres, those fibres are 
innervated, their entire lengths, by the nerve of the related 
arch. Ruge shows all those fibres of the hyal constrictor 
that are not interrupted by the most anterior linear apo- 
neurosis continuing onward to the dorsal edge of the con- 
tinuous muscle-sheet, and his descriptions lead one to 
conclude that these fibres are innervated, their full lengths, 
by the nervus facialis, while the fibres interrupted by the 
aponeurosis are only so innervated up to the aponeurosis. 
If the innervations thus ascribed to these muscles by 
Vetter, Tiesing, and Ruge are correct, and if my conclusions 
regarding these muscles are also correct, the constrictores 
superficiales of all fishes in which they are interrupted hy 
linear aponeuroses thus unexpectedly present typical examples 
of a muscle derived from one segment of the body being 
innervated bv the nerve of another segment; and here, not only 
would the innervation be definitely a secondary one, replacing 
an earlier and normal innervation, but the change of inner- 
vation would have taken place in definitely postembroyonic, 
if not in practically adult, stages. Furthermore, the secon- 
darily acquired innervation of different parts of the dorsal 
strands, or fibres, of the constrictores of the hyal and first 
branchial arches of Mnstelus would be by several different 
nerves, while the ventral portions of those same strands, or 
fibres, would be innervated by a single nerve. This certainly 
seems improbable, if not impossible, and nntil Vetter’s,. 
Tiesing’s, and Ruge’s statements have been properly con- 
trolled, it seems proper to conclude that the innervations 
given by them are incorrect, and that the muscle of each 
arch retains its primitive and normal innervation. That 
certain individual fibres of each constrictor are cut in two 
where they are crossed by the linear aponeuroses is practically 
certain, and in all such cases it is probable that that part 
of each muscle fibre that thus lost its connection with its 
motor nerve underwent paralysis and subsequent reduction. 
