ABBREVIATIONS. 



Vll 



The terms applied to the head-bones are largely used in descriptions of 

 Acanthopterygians. The accompanying woodcut, representing the skeleton of 

 a Perch's head, and copied from Cuvier and Valenciennes's great work on 

 Fishes, shows the position and names of the principal bones affording generic 

 and specific characters. 



Skeleton of Head of a Perch. 



/, frontal. 

 t, turbinal. 

 po, preorbital. 

 io, infraorbital ring. 

 mx, maxillary. 

 pmx, premaxillary. 

 m, mandible. 

 of, dentary bone. 



pt, posttyrnpanic. 

 s, suprascapula. 

 o, opercle. 

 so, subopercle. 

 pr, preopercle. 

 iop, interopercle. 

 br, branch iostegal rays. 



There are a few other words of frequent use in descriptions of Fishes that 

 require explanation. 



Pscudobranchi(g are a series of lamince attached, in many Teleostean fishes, to 

 the inside of the gill-cover opposite the gills, and are the remains of a 



