156 



Proceedings of the Royal Physical Society. 



bone which in the recent Sturgeon is called " praeoperculum " 

 by Mr W. K. Parker,^ although it seems to me and others to 

 be the same " jugal " element which we find appended to the 

 maxilla in Amia, Salmo, etc. In the Sturgeon it has also 





eg '==^ 



'^ PQ 'o 



^.^^ 



OJ CO ^, 



ri5 CO O 



'o Pm 3 

 S 6 to 



o ^ 



S^.2 I! 



been called " maxilla " by some who looked upon the real 

 maxilla as a " prsemaxilla," ^ and this seems to have been Sir 

 P. Egerton's view when he assigns a prsemaxilla as well as a 



1 "On the Structure and Development of the Skull in Sturgeons," Phil. 

 Trans., vol. 173 (1881), p. 172. 



'^ See Stannius, *' Handbuch der Zootomie der Wirbelthiere,'' erster Theil, 

 Die Fische, p. 53. 



