426 



FISHES. 



ing to the species ; in some they are exceedingly elongate, 

 twice as long as the fish, in others they are not longer or even 



Fig. 186. — Pcntancmus qulnquarkis, from the West Coast of Africa ami 

 tlie West Indies. 



shorter than the pectoral. It is evident from the whole 

 organisation of these fishes that they live on muddy bottom 

 or in thick water, such as is found near the mouths of great 

 rivers. Their eyes are large, but generally obscured by a 

 filmy skin, so that those feelers must be of great use to them 

 in finding their way and their food. The Polynemoids are 

 very useful to man : their flesh is esteemed, and some of 

 the species are provided with an air-bladder which yields a 

 good sort of isinglass, and forms an article of trade in the 

 East Indies. Some of these fishes attain to a length of four 

 feet. 



Fifth Division — Acanthopteeygii Sci/ENIforjies. 



The soft dorsal is riwrc, generally miicli more, derelojKd than 

 tlie s'pinous, and than the anal. No pectoral Jilaments ; head 

 with the mucifcrous cannls well developed. 



Also this division is composed of one family only. 



Family — Sci^enid^. 



Body rather elongate, c.om20Tessed, covered with ctenoid scales. 

 Latercd line continuous, and frequently extending over the caudal 



