JOHNSON, HABITS OF A CLIMBING CATFISH 



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in a down-stream direction. The final result would be the same as 

 though they were unprovided with a means of anchoring themselves at 

 will. But they are equipped with another and very efficient apparatus 

 for locomotion. The flat sucker mouth is half of the mechanism; the 

 other half is located on the belly. Under the skin of the ventral side, 

 just behind a line joining the pectoral fins, there is a triangular bony 

 plate to which are attached the ventral fins (Fig. 2). The main anterior 



Fig. 2. — Arges marmorattts Kegan ; ventral view 



ribs of these fins are broad and flattened, and the flat surfaces are thickly 

 studded with small, sharp teeth pointing backwards. The triangular 

 plate and its attached fins are free to move in a longitudinal direction 

 through a distance equal to about one-sixth of the length of the fish. 

 This movement is accomplished by ineans of four muscles in two pairs 

 attached to the plate; the anterior pair extending from their attachments 

 on each side of the plate forward to the middle point on the bony arch 

 just below the gill openings; the posterior pair extending from an 



