THE MYOLOGY OF POLYODON 
C. H. DANFORTH 
From the Anatomical Laboratory of Washington University 
TEN FIGURES 
I. INTRODUCTION 
Besides rather numerous incidental references to Polyodon, 
there are to be found in the literature a few papers that deal 
more or less specifically with the anatomy of this fish. Bridge 
(78, 796, °97) has worked on different aspects of the skeletal 
system, and the visceral skeleton and nerves have been studied 
to some extent by van Wijhe (’82). More recently work on the 
vascular system has been done by Allen (’07), Allis (11) and 
Danforth (712). A few more special papers might also be men- 
tioned. The myology, as a whole however, has apparently been 
left untouched until now. 
The present paper aims to supply a brief account of the mus- 
culature of Polyodon which may be available for comparative 
purposes or for future developmental studies. It is based chiefly 
on dissections of adult fish, about a meter in length, which had 
been preserved in formalin. The blood vessels of a part of 
them were injected. A few smaller individuals, three to four 
decimeters long, were studied and use was also made of serial 
sections of a 74 mm. specimen. 
For purposes of description the muscles are grouped under the 
following heads: Eye muscles, Muscles of the mandibular and 
hyoid arches, Muscles of the branchial arches, Hypoglossal mus- 
cles, Muscles of the trunk, Muscles of the median fins, Muscles 
of the pectoral arch, Muscles of the pelvic fin. 
The terminology of muscles in fishes has not yet become uni- 
form. In the case of cranial muscles I have followed the desig- 
nations of Vetter (’78) as applied to Acipenser wherever the 
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