i8o MARINE AND FRESHWATER FISHES 



a mane. In an allied, but still more extraordinary 

 Australian type (Phyllopteryx eques\ represented in the 

 accompanying engraving (Fig. 24), leaflike appendages of 

 the integument are produced so luxuriantly from various 

 points of the surface of the body that the animal is 

 scarcely to be distinguished from a branch of sea-weed. 



SUB-ORDER V.Plectognat/ii. 



Body covered with simple scales, scutes or spines, gills 

 pectinate, gill opening in front of the pectoral fins, very 

 narrow ; a soft dorsal fin developed posteriorly opposite to a 

 corresponding anal one ; ventral fins absent, or reduced to 

 one or more spines ; air-bladder without a pneumatic 

 duct 



FAMILY I. FILE-FISHES (Sclerodermi). 



Jaws armed with distinct teeth. Skin with scutes, or 

 rough ; elements of spinous dorsal and ventral fins usually 

 present. 



The fish belonging to this group are essentially inhabi- 

 tants of the tropical seas, solitary individuals representing 

 two species, the spotted File-fish (Balistes maculatus\ No. 

 190, and the Mediterranean File-fish (B. capriscus], No. 191, 

 having on rare occasions been taken as stragglers in British 

 waters. They are oblong compressed forms, remarkable for 

 the simple slit-like opening to the gill cavity, the armature of 

 their body, which consists of closely apposed polygonal 

 plates in place of overlapping scales and for the modification 

 of the first dorsal fin, which consists somewhat after 

 the manner of the Trumpet-fish (Centriscus), of an anterior 

 abnormally developed spine, and two or three other 



