170 



PALEONTOLOGY. 



Sab-Order 1.— CTENOIDEI. 



Exo-skeleton as ctenoid scales (fig. 76). 



This sub-order includes the existing families of the perch, 

 the bream, the gurnard, and the chcetoclont ; it will here 

 suffice to exemplify it by two genera, both of which are 



extinct. One 



'» (Semiophorus) 

 belongs to the 



Fig. 76. 



Scale of Percu 



(Recent). 



chetodont fa- 

 mily ; the other 

 (Smerdis) to the 

 Percoids. 



The genus 

 Semiophorus, 

 Ag. (fig. 77), is 



represented ex- 

 clusively by spe- 

 cies peculiar to 

 the tertiary de- 

 posits at Monte 

 Bolca. It is cha- 

 racterized by the 

 extreme height 

 or prolongation of the anterior part of the dorsal fin, D, and 

 for the correlated elongation of the slender-pointed ventral 



Fig. 77. 

 iSemiophorus velicans (Monte Bolca). 



