THE MYOLOGY OF POLYODON 145 
place Polyodon at the end of a line leading back through Acipenser 
and Seaphirhynchus to a type more primitive than the Selachians. 
The other view that the fin of Polyodon is in reality very primi- 
tive and that the radialia found here are comparable to those of 
an unpaired fin seems to the present writer quite as plausible. 
The musculature of the fin seems to present nothing against this 
latter view. 
LITERATURE CITED 
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Sei., vol. 9, pp. 79-125. 
Auuis, E. P. 1897 The cranial muscles and cranial and first spinal nerves in 
Amia calva. Jour. Morph., vol. 12, pp. 487-808. 
1911 The pseudobranchial and carotid arteries in Polyodon spathula. 
Anat. Anz., Bd. 39, pp. 257-262, 282-293. 
Braus, H. 1898 Ueber die Innervation der paarigen Extremititen bei Selachiern, 
Holocephalen und Dipnoern. Jena. Zeit., Bd. 31, pp. 239-468. 
Bripee, T. W. 1878 On the osteology of Polyodon folium. Phil. Trans. Roy. 
Soc. London, vol. 179, pp. 683-733. 
1896 The mesial fins of ganoids and teleosts. Journ. Linn. Soc., Zool., 
vol. 25, pp. 530-602. 
1897 On the presence of ribs in Polyodon (Spatularia) folium. Proc. 
Zool. Soc., London. 
Danrorts, C.H. 1912 The heart and arteries of Polyodon. Jour. Morph., vol. 
23, no. 3, pp. 409-452. 
Davivorr, M. von 1879-1880 Beitriige zu vergleichenden Anatomie der hintern 
Gliedmasse der Fische. Morph. Jahrb., vol. 5, pp. 450-520; vol. 6, 
pp. 483-468. . 
Dourn, A. 1884 Studien zur Urgeschichte des Wirbelthierkérpers. VI. Die 
paarigen und unpaarigen Flossen der Selachiern. Mitt. Zool. Stat. 
Neapel, vol. 5, pp. 161-195. 
Fursincer, M. 1895 Ueber die mit dem Visceralskelett verbundenen spinalen 
Musculen bei Selachiern. Jena. Zeitschr., Bd. 30, pp. 127-135. 
GEGENBAUR, C. 1898 Vergleichende Anatomie der Wirbelthiere mit Beruck- 
sichtigung der Wirbellosen. Leipzig. 
Marion, G. E. 1905 Mandibular and pharyngeal muscles of Acanthias and 
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Mauer, F. 1912 Die ventrale Rumpfmuskulatur der Fische. Jena. Zeit., Bd. 
49, pp. 1-118. 
