18 Synopsis of the Fresh Water Fishes, 



bone, and covered with moderate teeth, of which the row near 

 the posterior margin and those along the middle, extending from 

 the anterior angle, are largest; these are laterally compressed, 

 curved posteriorly for about two-thirds of their length, and 

 from this point, with a bolder curve, they advance forwards; 

 as the teeth approach the sides they lose this form, and begin to 

 assume a subcylindrical shape with the apices hardly uncinate. 



Branchial arches with the concave sides armed with com- 

 pressed bony papillae, which, on the first pair, are sometimes 

 dilated at the extremities. 



Branchiostegal rays five. 



Ojpercular apparatus with the bones entire ; operculum with 

 a blunt spine at the angle ; operculum, sub-operculum, cheeks, 

 and the upper part of head, to within a short distance of the 

 anterior borders of orbits, covered by large scales ; the scales on 

 the cheeks are in three or four rows. 



Naves simple, between the mouth and eyes. 



Lateral line interrupted ; the anterior portion near the back 

 and nearly parallel with it ; the second rectilinear, running along 

 the middle of the sides and the tail. 



Dorsal long, commencing at the nape, with the spinous por- 

 tion low, sub-equal, slightly increasing in height towards the 

 soft portion. The latter is much shorter than the spinous por- 

 tion, high, with the middle rays extended beyond the mem- 

 brane, and with the anterior and posterior rays decreasing in 

 length towards the extremities of the fin. 



Anal commencing below posterior spines of dorsal, with 

 three or four spinous rays increasing towards soft portion. The 

 central soft rays elongated with filiform extremities, and pro- 

 duced beyond the connecting membrane, like the dorsal fin. 



Both of these fins have the soft portions with their bases 

 covered by scales. 



Caudal with the base covered by scales ; the margin rounded 

 or truncated. 



Pectorals large. 



