TFFK FRESH-WATER I-'ISHKS oF 



eye by twice the orbital diameter. The nasal opening is single, nearer the 

 eye than the snout ; it is defended at its front edge by a fold of skin, which 

 can close it like a valve. The small mouth is nearly horizontal and horse-shoe- 

 shaped ; it does not reach as far back as the nasal valve. The rounded ex- 

 tremity of the snout projects over the mouth, which is covered by lips 

 that are not fleshy. Both pairs of barbels are short, the longer barbels at the 



Fig. 51. AULOPYGE HUGELII (HECKEL). FEMALE. 



Fig. 52. UNDER SIDE OF THE HEAD OF 

 AULOPYGE HUGELII. FEMALE. 



corner of the mouth being barely equal to the diameter of the eye. The depth 

 of the body at the tail is one-third the greatest depth below the dorsal fin. 



The dorsal fin commences nearer to the tail than the head. It is opposite 

 the ventral fin, is higher than long, though it is fully half as long as the head ; 



it is truncate behind ; its second ray is re- 

 markably broad and strong, and the third is 

 deeply and strongly serrated down the entire 

 length at its hinder edge. All the succeed- 

 ing rays are jointed, and divide three times. 

 The anal fin is posterior to the end of the 

 dorsal, is as high as long, with a short base, 

 and is truncate behind. This species is distinguished 

 from all other known fishes by the remarkable con- 

 dition of the anal aperture in the female. 



The intestine and the urogenital system both leave 

 the body in a thick, fleshy tube, which is united to the 

 first ray of the anal fin in front, and near the ex- 

 tremity of that ray this tube has two openings, the 

 urogenital being posterior. A somewhat similar con- 

 dition has been described in the male of the American 

 genus Anableps. The succeeding rays of the anal fin divide dichotomously. 



* 



Fig. 53. AULOPYGE HUGELII: 



LATERAL LINE AND SKIN, 

 SHOWING PIGMENT SPOTS. 



