On the Anatomy and Pbylogenetic Position of Polypterus. 



399 



Comparison. 



The close similarity which exists between the nerves of Poly- 

 pterus and the Selachii has been already mentioned by van Wijhe 

 in the preface to the German edition of his work on Ganoids so that 

 little remains to be said on this point. I wish however further to 

 emphasize the exceeding primitiveness of Polypterus in the structure 

 of its ophthalmicus profundus. It is far more primitive than in the 

 majority of the Selachii. On account of recent work on the nervous 

 systems of Urodeles especially by von Plessen and Rabinovicz and 

 Wilder it is possible to institute careful comparisons of Polypterus 

 with Amphibian forms. This however can best be done by actual 

 comparison of figures so I have endeavoured to make some of Poly- 

 pterus as clear as possible. The nomenclatures are as follows: 



VON P. u. R. 

 III. Nasalis 



Wilder 

 R. ophth. prof. 



here 

 R. ophth. prof, (median) 



Zweig a 



Nasalis internus (part.) 



Main branch 



Nas. ext. 



External branch 



R. comm. c. supramx. sup. 

 R. supramx. inf. 



R. mx. sup. 



R. pal. 



Nebenganglion 



R. frontalis 



R. supramx. sup. 



Zweige o. w. 



R. hyoideo-mandib. 



R. comm. c. Gloss 



R. buccalis mit N. der 



h. m. begleitet 

 R. alveolaris 



R. pal. 



R. ophth. sup. 



R. m. s. 



Nasalis int. (part.) 



R. jugularis 



Same 



R. mand. 



R. alv. 



R. palatinus 



Ganglion 



R. 0. s. 



R. buccalis i) 



Main stem 



R. hyoideus 



Jacobsonian comm. 



R. mand. ext. 



R. mand. int. 



It will thus be seen that the nerves of Polypterus and Urodeles 

 are of the same type and one has to search for differences rather 

 than similarities. Differences are in Urodeles seen in the ophthalmicus 

 profundus which has fused with the trigeminal ganglion and lost to 

 a considerable extent its commissures with the ophth. sup. Differences 

 are also seen in the mandibular supply. The course of nerves in 

 Polypterus is more primitive and on the whole anastomoses are less 

 frequent and marked. 



1) cf. Stannius "Der Ramus buccalis, dem R. subcutaneus 

 m a 1 a e höherer Wirbelthiere vergleichbar", Zootomie der Fische und 

 Amphibien, 1, p. 158. 



