Charles R. Stockard 483 
GENERAL DISCUSSION OF WorRK AND VirEws RELATING TO THE 
MARSIPOBRANCHILI. 
1. The morphology of the myxinoids has been so extensively studied 
that its literature has become almost cumbersome. The earliest reference 
to these animals that I have been able to find is that by Gunnerus in 
1762. He described Myxine glutinosa under the name “ Sleep-Marken.” 
He described the tooth plate as a jaw, and also found the two openings, 
mouth and nose, leading into the pharynx; the remarkable “tongue” mus- 
cle-apparatus he called a wind-pipe or air tube. Gunnerus also described 
the gills of each side calling them lungs. His work is reviewed in the 
papers of J. Miiller, 1835, and P. Fiirbringer, 1875. 
In 1790 A. J. Retzius also described the tooth plate as a jaw and the 
club-muscle as a wind-pipe. He classed Myxine among the fishes instead 
of with the worms and molluscs as some previous writers had done. 
Abildgaard, 1792, mentioned the “wind-pipe” of Gunnerus as the 
club-shaped jaw muscle and called the tooth plate, Zungen-Zahne, a lower 
jaw, stating that it was strengthened and moved as such. Abildgaard 
gave the first correct description of the gills, stating that on each side 
a canal opened to the outside after receiving the six canals of the gills and 
these gills through another set of six canals connected with the throat. 
He also traced the gill vessels. 
Bloch, 1789, described two parts of the club muscle, the outer hollow 
circular muscle, and the longitudinal one. J. Miiller states that he gave 
their connection incorrectly, claiming both to be fastened to the jaw 
bone, by which Bloch meant the tooth plate or “ tongue;” while in fact 
Miiller claims the first to be attached to the tongue cartilage and the 
second to the tongue itself. 
Home in 1815 described rather fully the gill system and compared 
the organs of Bdellostoma and Myxine. Miiller states that in his 
explanation of figures Home correctly said that the teeth belonged to 
the tongue, he also described the connected muscle-body as a tongue 
muscle apparatus. P. Fiirbringer says that Home first corrected the 
error of calling the dental-plate the jaw by recognizing in it a tongue. 
In the present paper I shall endeavor to show on the other hand that 
it was Home and subsequent workers up until 1900 that were in error 
when they called this organ “ tongue,” and that the earliest workers were 
correct in interpreting the dental-plate as a jaw. 
I have given this brief historical review for the purpose of showing 
that the idea that the dental-plate is a lower jaw and not a tongue was 
the oldest or first interpretation of this organ and not a new 
