86 CLASS IV. ORDER IV, 



covers three-leaved, scaly, serrated ; dorsal-fin 

 spiny on the forepart ; scales (in most species) 

 hard and rough. 



HOLOCENTRUS, habit as Perca ; gill-covers sca- 

 ly, serrated and aculeated ; scales hard and rough. 



BODIANUS, (boclian,) habit as Perca ; gill-cov- 

 ers scaly, not serrated, aculeated ; scales smooth. 



SCOMBER, (mackrel,) body oblong, smooth, 

 sometimes carinated by the lateral line ; finlets 

 (in most species) above and below towards the 

 tail. 



GASTEROSTEUS, (stickleback,) body somewhat 

 lengthened ; dorsal-spines distinct ; ventral fins 

 spiny ; abdomen carinated or shielded on the 

 sides, and bony beneath. 



MULLUS, (surmullet,) head compressed, scaly : 

 mouth bearded ; gill-membrane three-rayed ; bo- 

 c-y covered with large subdeciduous scales. 



TRIGLA, (gurnard,) head large, mailed and 

 marked by rough lines ; gill-covers spiny ; gill- 

 membrane seven-rayed ; finger-form processes (in 

 most species) near the pectoral-fins. 



TRACHICHTHYS, head rounded in front ; eye 

 large ; mouth wide, toothless, descending ; gill- 

 tnembrane furnished with eight-rays of which the 

 four lowermost are rough on the edges ; scales 

 rough ; abdomen mailed with large carinated 

 scales. 



ORDER 4. ABDOMINALES. 



Gill-membranes with bony rays ; ventral-fin^ 

 back of the pectoral. 



COBITIS, (loche,) mouth bearded (in most spe- 

 cies) ; eyes situated in the upper part of the head : 

 body nearly of equal thickness from head to tail ; 



